In 2003, Dr. Lihong V. Wang at Washington University introduced one of the most exciting technologies we’ve had the chance to see in a long while. By combining ultrasound and light absorption, Wang and colleagues developed a new method that makes multicontrast images of biological tissues several inches below the skin. Among others, this allows specialists to see cancer in action with unprecedented detail and provide a faster and more accurate diagnosis. Recently, Want and colleagues at Washington University published a paper that refines this innovative optical imaging method by using what they call “time-reversal” technology that allows for better-focused light in tissue, such as muscles and organs.
Peering through the skin
Called photoacoustic tomography (PAT), the technique achieves imaging depth by combining the spatial resolution of ultrasound with the high contrast resulting from light absorption by colored molecules such as hemoglobin or melanin. Typically, high-resolution optical imaging technology allows researchers to see about 1 millimeter deep into the body. PAT, however, can peer through biological matter at depths as big as 7cm!
What makes PAT really exciting is its ability to reveal the use of oxygen by tissues. When oxygen is burned in excess (hypermetabolism), this is usually a telltale sign that cancer is lurking. Diabetes also causes hypermetabolism. By using PAT, doctors can analyze patient tissue and provide an early-warning diagnosis without using a contrast agent – a big game changer!
The key to PAT’s success is converting light into sound waves, which scatter a thousand times less than light. A nanosecond-pulsar laser is used to this end, which is directed at the tissue. The thermoelastic expansion of the tissue causes the photons to convert into sound waves, later used to form images with a resolution associated with the ultrasound wavelength at tissue depths never before possible. Because scattering does not destroy photons, the technique makes it possible to reach a depth of about 7 cm.
Of course, there are many methods to examine living cells inside the body. Optical microscopy is used to examine organelles and cells, and nonoptical imaging techniques such as x-ray tomography are used for tissues and organs, but between these two domains – the macro and micro – a huge divide exists in scale. “Using the same contrast allows the same landmark features to appear in images acquired across length scales with different spatial resolutions,” Wang says.
With help from exogenous (introduced) contrast agents, PAT can image tissues such as lymph nodes that otherwise would blend with their surroundings. A huge improvement comes in sentinel node biopsy. Sentinel nodes are the nodes nearest a tumor, to which cancerous cells first migrate. To perform a biopsy, a surgeon injects a dye, a radioactive substance or both near a tumor. The body treats both substances as foreign, so they flow to the first draining node to be filtered and flushed from the body. Using Wang’s technique, however, a simple optical dye is injected that shows up clearly in photoacoustic images a vast improvement over its invasive counterpart.
Since 2012, the Washington University team has gone to great lengths to improve and refine their PAT tech. Reporting in the Nov. 2 issue of Nature Photonics Advance Online Edition, Wang and colleagues write how they are now using time-reversed adapted-perturbation (let’s call it TRAP for short) optical focusing to image movement in real time.
When light moves through stationary tissue it shows different than that that passes through moving tissue, like blood. The new refinement takes two successive images, then subtracts the stationary-moving light, retaining only the scattered light due to motion. Through a process called time-reversal, the light is then jettisoned back to its original sources where it becomes focused. This allows the PET technique to be a lot more efficient at tracking moving objects. Also, images can now be taken from greater depths.
Journal Reference: Cheng Ma, Xiao Xu, Yan Liu & Lihong V. Wang. Time-reversed adapted-perturbation (TRAP) optical focusing onto dynamic objects inside scattering media. Nature Photonics (2014) doi:10.1038/nphoton.2014.251
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Scivita Medical brought the products of this year: 3D imaging system, 4K ultra-high-definition endoscopic system and disposable electronic ureteropyeloscope system to participate in this Spring ICMD in Shanghai.
The new concept created by Scivita Medical: 4K+3D laparoscope system combining 4K ultra-high-definition image with 3D effect yields brilliant results and wins unanimous praise of the professionals.
During the exhibition, many peers in the industry gathered in front of the exhibition booth, to explore the application and development of the latest medical technology.
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Original 3D imaging system
One highlight in this exhibition: disposable electronic ureteropyeloscope system
Disposable electronic ureteropyeloscope system of Scivita Medical has won the professional audience with its image processing technology matching the image quality of endoscopic products for repeated use, accurate operating performance for clinical use, smooth and reliable endoscope engineering design, as well as perfect function details.
Scivita Medical embraces the mission of “resolving the clinical problems in a safe and effective manner”, and quality guideline of “seeking for excellent quality, and unlimited innovation”, so as to provide high-quality products and considerate and close services for the medical personnel worldwide, and contribute to the health of the human beings.


Apple is expected to use Fresnel lenses in its rumored augmented reality headset to increase the device’s field of view and reduce pressure, according to analyst Ming-Chi Kuo.
In a note to investors Monday seen by AppleInsider, Kuo says that Apple will use Fresnel lenses as the design solution for the device ‘s ultra – short focus length lenses. That increases the optical performance of the machine while cutting weight and thickness.
“We believe that Apple will further use the Fresnel hybrid lens design to enhance the optical performance of a Fresnel lens (e.g., improve vignetting and optical artifacts), and each hybrid Fresnel lens is made up of three stacked Fresnel lenses,” Kuo said. writing.
The analyst said the micro-OLEDs used in Apple’s head-end device could compensate for the light caused by the adoption of Fresnel lenses. He says that with the high brightness of the micro-OLEDs, and says that the platform could provide an “innovative [augmented reality and mixed reality] experiences. ”
Apple’s proper system could eliminate some of the cases of custom VR or AR headphones with Fresnel lenses, which typically weigh around 300 to 400 grams and sport as a more form factor. greater. One of the main design challenges among VR headset manufacturers is to achieve a fairly thin and lightweight design.
However, Kuo says that one of the main competitive advantages of video-see-through augmented reality devices, such as the “Apple Glass” rumor, is that field-of-sight requirements are typically lower than headsets. VR. Because of this, they can be thinner and lighter.
The analyst says the use of Fresnel lenses will allow Apple to achieve a better balance between the shape factor of its headset and its field of view. The Apple HMD rumor device could weigh around 150 grams or a little less, he said. Each Fresnel hybrid lens for one eye is made up of a stack of three Fresnel lenses. Since each Apple headset uses two Fresnel hybrid lenses, that equates to a total of 10 lenses per device.
“Apple HMD Fresnel lens material is plastic. Because of the custom material and coating, the light transmission is not inferior to glass,” Kuo writes. “It also means that the [average selling price] it is not low. ”
Kuo names Young Optics and Genius as Fresnel lens suppliers for Apple’s headset device. He believes Young Optics is the main supplier, since Apple and the company started working together and investing more resources earlier than Genius.
Earlier in March, Kuo speculated that Apple’s AR headset could feature advanced eye tracking and possibly magazine recognition technology.
Apple is thought to be working on at least two separate headset devices, including a visor-like mixed reality device that Kuo says could be debated in 2022 for an estimate of $ 1,000. That device could then be followed by the thinner and lighter “Apple Glass” in 2025, and by AR contact lenses after 2030.


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The Optical Chassis is strongly recommended for combination with the optical microscope.


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OMERO.server image rendering
A major requirement for any image data application is the ability to display images. In most applications, this is achieved by reading pixel data from a filesystem and then mapping the pixel data to the 256 grey level available on most computer display monitors. It is common in some experiments to record and display multiple channels at once. Typically three, four, or even five separate images must be mapped, and then presented as a color image for painting on a monitor. Because these operations can require many thousands of operations and must be displayed rapidly to support the display of time-lapse movies, most image display software applications use a high-speed graphics CPU and dedicated hardware for image rendering and display. This requirement limits the deployment of these applications to high-powered workstations.
OMERO.server includes an image server, a software application that delivers rendered images to a client. This ensures that client applications can display image data. The OMERO Rendering Engine (OMERO-RE) has been designed to minimize the amount of data transferred to the client and thus removes the requirement for a specific graphics CPU, allowing high-performance image viewing on standard laptop computers. The OMERO-RE achieves this by limiting data transfer times by being close to the data, using highly efficient network transfer protocols, utilizing modern multi-processor and multi-core machines to provide the data to clients in a format that is as efficient to display as possible. OMERO-RE is multi-threaded and can use multi-core servers to simultaneously render individual channels before assembly into a final color image ready for transfer to the client. The use of the RE is not mandatory. If a client needs to have the full pixel data, it can. This OriginalPixels facility is used for client-side analysis, like that performed in the OMERO.insight measurement tool.
Transfer of image data even after rendering can limit performance, especially when accessing data remotely on connections with limited bandwidth (e.g. domestic ADSL). Therefore the OMERO-RE contains a compression service with an API that allows a client adjustable compression providing minimal image artefacts and a 20-fold range of data size to the client.
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We report a new optical vortex phase-shifting method for digital holography, in which an optical vortex mode is taken as the reference beam for holographic recording, and the required phase shifts are directly generated by rotating the vortex mode. In digital reconstruction, the complex amplitude of the object wave can be retrieved by use of the conventional phase shifting algorithm on condition that the digital illumination beam is replaced by an vortex beam with the same topological charge as the reference used. Both the theoretical analysis and experimental results demonstrate the feasibility of this approach.
©2004 Optical Society of America
In digital holography, holograms are captured by a CCD camera and reconstructed by a computer through diffraction integral [1, 2]. Compared with conventional holography; it saves the trouble of photographic processing and shortens the exposure time. Some other salient features include the freely focusing to yield the image at arbitrary position and the quantitative retrieving for the phase distribution of the object wave [3–6]. Lower resolution of CCD array than photographic materials, however, limits the use of an off-axis recording geometry for separating the reconstructed image from the conjugate replica and the zero diffraction order. Phase-shifting digital holography that employs the in-line setup together with phase shifts of the reference wave overcomes this issue by directly retrieving the complex amplitude in the CCD plane [6–11].
Realizing exact phase shifts is of great importance for phase-shifting digital holography [12,13]. Some phase-shifting techniques suitable for different applications have been proposed. For example, the phase shifts can be produced by moving a mirror, tilting a glass plate, moving a grating, rotating a wave plate, or using computer generated holograms [14–16].
In this letter we propose a new avenue for phase-shifting digital holography based on optical vortices. We use an optical vortex (OV) beam as the reference beam for holographic recording. This special helical wavefront can be generated by a spiral phase plate (SPP)  or a computer-generated hologram (CGH) [18, 19]. At the same time, the phase shifts required in phase-shifting algorithm can be directly produced by turning the SPP to different angles around the beam axis. Despite substituting an OV reference beam for conventional plane or spherical wave in recording a digital hologram, no special difficulties are brought for the digital reconstruction, because the OV beam is easily produced and adjusted in computer. By contrast, this substitution may be especially useful in interferometric null testing of aspheres [20, 21] and in research on dynamics of optical vortices in linear or nonlinear materials. In the following description, this method will be called OVPS (optical vortex phase-shifting) method for short.
The basic setup for the OVPS method is shown in Fig. 1. An expanded laser beam is divided by a splitter into two beams. One beam illuminates the test object to form the object beam Uo. Another beam is incident vertically on the SPP with a phase-only transmittance of exp(ilϕ), where ϕ is the azimuth angle and l is an integer known as the topological charge. The OV beam UR emerged from the SPP interferes with the object beam U0 in the CCD plane to form a hologram, which is recorded by the digital CCD camera. In order to use the phase-shifting algorithm for retrieving the complex amplitude of the object wave from the recorded holograms, some global phase shifts of the reference wave have to be introduced stepwise. This can be achieved by use of the flexibility of the SPP in the phase shift, that is, the global phase of the reference beam can be changed stepwise by rotating the SPP around its axis. On rotation of the SPP through an angle θ, the complex amplitude of the OV beam in the CCD plane can be written as
where A(r) is the amplitude, which is only dependent on the radial coordinate. We can see that the rotation of an angle θ corresponds to a definite global phase shift of Δφ = lθ. Obviously, an optimal choice of the topological charge of the SPP should be l = 1 for our purpose; in this situation the global phase shift is exactly equal to the turned angle of the SPP.
Figures 2(a), (b), (c) and (d) show the phase distributions of an OV beam with l=1, corresponding to the turned angle θ is equal to 0, π/2, π and 3π/2, respectively. Figure 2(e), (f), (g) and (h) give the interferograms formed by the above four OV beams with an oblique coherent plane wave, respectively. It can be seen from the interference fringes that the turned OV beams really have the same wave fronts except for a global phase shift in order. These phase shifts satisfy the requirements for four-frame phase-shifting digital holography . We can derive the complex amplitude distribution Uh(x,y) of the object wave on the CCD plane from four phase-shifted holograms In(x,y, θn) as
The reconstruction of the object at a distance zo is performed generally by the Fresnel transformation of the derived complex amplitude
We carried out experiments to demonstrate the method described above. The experimental setup is shown in Fig. 1. It is essentially a Mach-Zehnder interferometer. A 30-mW He-Ne laser at a wavelength of 632.8 nm was used as the light source. In principal, we could use a spiral phase plate (SPP) or a computer-generated hologram (CGH) to generate the required OV. Of course a carefully designed SPP could be a good choice in this purpose. In our experiments, however, the SPP shown in Fig.1 was replaced by a CGH of an optical vortex with l = 1 just because of the limitation of our experimental condition. This CGH was formed by interference of the required OV with an oblique plane wave in computer and was dynamically displayed onto a programmable spatial light modulator (SLM) with 1024×768 pixels (each pixel has a 18 μm × 18 μm size). In general, several reconstructed wavefronts (as different diffraction orders) emerge from the CGH. The first diffraction order of particular interest is selected by a spatial filter and is taken as the reference beam UR. Quantitative rotations of the reconstructed optical vortex can be implemented by displaying the CGHs with differently angled helical wavefront onto the SLM in a proper sequence. The interferograms formed by the vortex reference and the object waves were recorded by a CCD camera.
To quantitatively check the phase-shifting values, we first measured the global phase shifts versus the turned angle of the optical vortex by use of the Fourier method [22, 23]. Figure 3 shows our experimental result, in which the solid line is the theoretical curve and the circles are the measured values. The consistency of our experiment with the theory proves the validity of this phase-shifting method.
Next we carried out a phase-shifting digital holographic experiment. A transparency of two Chinese characters is used as the object. We adopt the four-step phase-shifting algorithm described in Eqs. (2) and (3), and the required phase shifts are generated by four CGHs with different angled optical vortices as shown in Fig. 2(a), (b), (c) and (d), respectively. After a set of holograms at four phase-shifting steps has been recorded on the CCD, the complex amplitude of the image can be calculated in terms of Eq. (2). Figure 4(a) shows the photo of the object (a Chinese word meaning “kindheartedness”). Figure 4(b) is one of four digital holograms recorded with the CCD camera. Figure 4(c) gives the image directly reconstructed by the hologram shown in Fig. 4(b). It is obvious that the reconstructed object wave is seriously contaminated by the conjugate image and the zero diffraction order. To eliminate this kind of contamination, we derive the complex amplitude of the object wave by Eq. (2). Figure 4(d) shows the final image reconstructed by the complex amplitude derived from our four digital holograms, in which the influences of the conjugate and zero diffraction parts are removed successively. This result implies that the precision of the phase shifts with the OVPS method is good enough for phase-shifting digital holography.
In digital retrieval of the complex amplitude of the object wave, we have to create an optical vortex as the illumination beam in computer. Theoretically, only when the illuminating vortex is the same as the reference vortex used in recording process, the complex amplitude of the object wave could be exactly retrieved, that is to say, the illumination vortex and the reference vortex have both the same topological charge and the same central point in the holographic plane. Keeping the same topological charge is easy. Locating the central point of the illumination vortex, however, brings a small error in general, which depends on the precision of determining the central point of the reference vortex in the CCD plane. In practical experiments, we can locate the central point of the reference vortex with the precision of two pixel spaces by use of the interference fringes between the reference vortex and a plane wave. Figures 5(a), (b), (c) and (d) give four reconstructed images of the holograms discussed in Fig. 4 when the location error is set on purpose to 8 pixels, 12 pixels, 16 pixels and 32 pixels, respectively. It can be seen that the reconstructed images keep a good quality if only the location error for a digital hologram with 1024×1024 pixels is less than 12 pixels, which implies that a location error of two pixels in practical experiments is allowed for good reconstruction in our OVPS method.
In conclusion, we presented and demonstrated the idea of optical vortex phase-shifting holography, named OVPS method, which allows us to conveniently realize arbitrary global phase shift by rotating an optical vortex around its axes. In addition, optical vortices are intriguing special optical structures with helical wave front and well-defined orbital angular momentum (OAM), which have been widely studied in different research fields [24–26]. Some of their fascinating properties have been found and many possible applications were demonstrated, which involve trapping of atoms or mesoscopic particles, driving microoptomechanical pumps, processing quantum information, generating optical vortex solitons, and so on. We believe that it is also a meaningful experiment to take an optical vortex as the reference beam in digital holographic recording. This OVPS method could offer a new approach for applications of the phase-shifting digital holography in measurement of the OAM and in research on the dynamics of the optical vortices in linear or nonlinear materials.
This work is supported in part by the NSFC under Grant Nos. 10474043, 90101030 and 10325417 (“Excellent Youth Foundation”) as well as the Research Foundation for the Doctoral Program of Higher Education under Grant No. 20030284012. Corresponding author H. T. Wang’s email address is email@example.com.
References and links
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5. S. Grilli, P. Ferraro, M. Paturzo, D. Alfieri, P. D. Natale, M. D. Angelis, S. D. Nicola, A. Finizio, and G. Pierattini, “In-situ visualization, monitoring and analysis of electric field domain reversal process in ferroelectric crystals by digital holography,” Opt. Express 12, 1832–1842 (2004). http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-9-1832 [CrossRef] [PubMed]
6. I. Yamaguchi and T. Zhang, “Phase-shifting digital holography,” Opt. Lett. 22, 1268–1270 (1997). [CrossRef] [PubMed] S. Lai, Brian King, and M. A. Neifeld, “Wave front reconstruction by means of phase-shifting digital in-line holography,” Opt. Commun. 173, 155–160 (2000). [CrossRef]
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8. S. Lai, Brian King, and M. A. Neifeld, “Wave front reconstruction by means of phase-shifting digital inline holography,” Opt. Commun. 173, 155–160 (2000). [CrossRef]
9. I. Yamaguchi, J. Kato, S. Ohta, and J. Mizuno, “Image Formation in Phase-Shifting Digital Holography and Applications to Microscopy,” Appl. Opt. 40, 6177–6186 (2001). [CrossRef]
10. L. Z. Cai, Q. Liu, and X. L. Yang, “Generalized phase-shifting interferometry with arbitrary unknown phase steps for diffraction objects,” Opt. Lett. 29, 182–185(2004). [CrossRef]
11. L. Z. Cai, Q. Liu, Y. R. Wang, and X. L. Yang, “Simultaneous digital correction of amplitude and phaseerrors of retrieved wave-front in phase-shifting interferometry with arbitrary phase errors,” Opt. Commun. 233, 21–26(2004). [CrossRef]
13. C. S. Guo, L. Zhang, H. T. Wang, J. Liao, and Y.Y. Zhu, “Phase-Shifting Error and Its Elimination in Phase-Shifting Digital Holography,” Opt. Lett. 27, 1–3 (2002). [CrossRef]
14. C. C. Jin, N. K. Bao, and P. S. Chung, “Application of a novel phase-shift method using a computer-controlled polarization mechanism,” Opt. Eng. 33, 2733–2737 (1994). [CrossRef]
16. C. S. Guo, Z. Y. Rong, H. T. Wang, Y. R. Wang, and L.Z. Cai; “Phase-Shifting with Computer-Generated Holograms Written on a Spatial Light Modulator,” Appl. Opt. 42, 6975–6979(2003). [CrossRef] [PubMed]
17. M. W. Beijersbergen, R. P. C. Coerwinkel, M. Kristensen, and J. P. Woerdman, “Helical-wavefront laser beam produced with a spiral phase plate,” Opt. Commun. 112, 321–327 (1994). [CrossRef]
19. J. Arlt, K. Dholakia, L. Allen, and M. J. Padgett, “The production of multiringed Laguerre-Gaussian modesby computer-generated holograms,” J. Modern Opt. 45, 1231–1237 (1998). [CrossRef]
20. J. C. Wyant and V. P. Bennett, “Using Computer Generated Holograms to Test Aspheric Wavefronts,” Appl. Opt. 9, 2833–2839(1972). [CrossRef]
22. K. A. Goldberg and J. Bokor, “Fourier-transform method of phase-shift determination,” Appl. Opt. 40, 2886–2894 (2001). [CrossRef]
23. C. S. Guo, Z. Y. Rong, J. L. He, L. Z. Cai, and Y. R. Wang, “Determination of global phase shifts betweeninterferograms by use of an energy-minimum algorithm,” Appl. Opt. 42, 6514–6519(2003). [CrossRef] [PubMed]
24. L. Allen, M. P. Padgett, and M. Babiker, “The orbital angular momentum of light,” Progress in Optics 39, 291–372 (1999). [CrossRef]
26. Z. Chen, H. Martin, E. D. Eugenieva, J. Xu, and A. Bezryadina, “Anisotropic Enhancement of Discrete Diffraction and Formation of Two-Dimensional Discrete-Soliton Trains,” Phys. Rev. Lett. 92, 143902 (2004). [CrossRef] [PubMed]
27. K. Ladavac and D. G. Grier, “Microoptomechanical pumps assembled and driven by holographic optical vortex arrays,” Opt. Express 12, 1144–1149 (2004). http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-6-1144 [CrossRef] [PubMed]


Contact lenses are so-called because people wear contact lenses in contact with their eyes. People are more likely to use contact lenses instead of using eyesight sunglasses. People use contact lenses for a wide range of purposes. The majority of the people have eye issues so they cannot see without some aid. For this purpose, people have to use contact lenses. Moreover, the majority of people use contact lenses for fashion purposes.
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A telescope is mounted to facilitate easy tracking of celestial objects as they move across the night sky. One axis (the polar axis) is aligned to the celestial pole (parallel with Earth's axis) and the other (the declination axis) is oriented at right angles to it.
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The wavefront reconstruction of hologram and holographic stereogram are analyzed to compare their imaging properties, and 'phase added stereogram' (PAS) is proposed as a technique for the calculation of computer generated hologram (CGH). Applying PAS, computer graphics techniques, for example, surface shading and hidden surface removal are easily applied in CGH generation process. The amount of computation is reduced compared with actual hologram calculation, and the quality of reconstructed image is superior to that of holographic stereogram. The theoretical expression of PAS is presented, and experimental results are also demonstrated.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.


A passively Q-switched S-band fiber laser is proposed and demonstrated using a thulium-doped fluoride fiber as laser gain medium. The proposed design possesses significant advantages including broader tuning wavelength range as compared to previously reported Q-switched S-band lasers. The laser cavity is configured in a simple forward-pumped ring design with a 1400 nm single upconversion pumping scheme. Q-switching is achieved using a polyvinyl alcohol/nitrogen-doped graphene nanosheet (PVA–N-Gns)-based thin-film saturable absorber. Stable Q-switched pulses are obtained at a center wavelength of 1504.7 nm over a pump power range from 101.8 to 280.6 mW. The generated pulses have a maximum pulse repetition rate of 36.85 kHz and minimum pulse width of 4.8 μs at the pump power of 280.6 mW. The maximum pulse output power of 1.30 mW indicates a laser efficiency of approximately 0.63% while a signal-to-noise ratio of 57 dB shows pulse stability. The ability of the proposed cavity design to produce broad wavelength tunability range from 1450 to 1510 nm make it highly suitable for various application in the S and S + band regions.
- Nitrogen-doped graphene
- Passive Q-switched


The Challis is perfect for those seeking a tighter fit and a slightly smaller lens profile. This 8-base wrap utilizes our premium ChromaPop and Techlite glass lens technologies for unparalleled optical clarity. Integrating premium spring hinges into the thin, flexible temples, this piece is perfect to accompany you down the road less traveled. Tortoise frame. Imported.
- Tighter fit
- Slightly smaller lens profile
- 8-base wrap
- ChromaPop and Techlite glass lens technologies
- Premium spring hinges
- Thin, flexible temples


At our centre in N16, Askew Eyewear checks for astigmatism in your regular eye test.
What is astigmatism?
Like short and long-sightedness, astigmatism is a problem in the way your eye focuses light. It happens when the cornea or the lens of your eye is not perfectly curved. This can cause your eye to focus images in two places on your retina, instead of one.
Astigmatism is very common, and can be corrected with the right lenses or contact lenses.


Researchers at the University of Maryland have developed a system that essentially turns the human eye into a mirror. The research team managed to convert what the person is looking at into a 3D scene by sequentially recording the images reflected on the human eye through binoculars.
A key element of the researchers’ technique is that humans are not stationary. The movement of the head, even if it is very small, creates different perspectives of the opposite scene on the eyes, and thus the process of virtual reconstruction of the scene becomes easier.
When training their neural network to deal with the complexity of iris tissues and solve the problem of low-resolution light reflection, researchers used corneal state optimization and iris tissue decomposition.
written by TechSpot, researchers succeeded in reconstructing 3D scenes using data obtained from the human eye with different colors. This research team has shared a video of their prototype system, which looks very interesting and scary.
It is worth mentioning that the initial results of the 3D scene creation system based on light reflection on the human eye were obtained in laboratory conditions with ideal light conditions and deliberate head movement. In addition, the recorded results were better than the artificial eye.
The researchers also correctly emphasized that the human eye is a source of information that is not considered in the world around us. It is very interesting to imagine what role the said technology will play in criminal cases without evidence.


|Publication number||US5483347 A|
|Application number||US 08/067,500|
|Publication date||Jan 9, 1996|
|Filing date||May 19, 1993|
|Priority date||May 19, 1993|
|Publication number||067500, 08067500, US 5483347 A, US 5483347A, US-A-5483347, US5483347 A, US5483347A|
|Inventors||Joerg W. Hollmann|
|Original Assignee||Hughes Aircraft Company|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (4), Referenced by (22), Classifications (5), Legal Events (9)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention generally relates to a non-contact measurement apparatus and, in particular, relates to one such non-contact measurement apparatus having a bifurcated bundle of optical fibers, a first portion of which are adapted to receive light from a light source and a second portion of which are adapted to convey light to a light detector.
In general, one of the more common methods of optically determining the thickness of a lens, or other reflective surface, is by laser interferometry. In such an instrument, the laser is directed toward the surface and the reflected interferogram is formed in accordance with the rules of light cancellation or reenforcement depending upon the phase of the signals. For example, if the reflected light is one hundred and eighty degrees out of phase with the incident light the light reflected is canceled and a dark ring is exhibited on the interferogram. It is well known that laser interferometers are capable of measuring very small changes in the thickness of an optical material. However, such techniques are quite expensive and introduce problems relating to eye safety. Further, such techniques, to operate most efficiently, require a highly reflective surface.
Other methods and instruments for measuring the thickness of lenses include ultrasonic systems and astigmatic and knife edge focus systems. Typically, however, ultrasonic systems od not have high accuracy although they are relatively inexpensive. Astigmatic and knife edge focus systems are typically used in data storage systems and are affected by both surface tilt and surface quality.
Hence, it is highly desirable to provide a non-contact measuring apparatus for measuring the thickness of an object that is highly accurate and relatively inexpensive.
Accordingly, it is one object of the present invention to provide a non-contact measuring apparatus that overcomes the above-recited drawbacks of similar conventional apparatus.
This object is accomplished, at least in part, by a non-contact measuring apparatus having a bifurcated bundle of optical fibers, a first portion of which is adapted to convey light from a light source and direct it toward a surface to be measured and a second portion of which is adapted to convey light to a detector such that the light intensity received via the second portion is indicative of the position of the surface.
Other objects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description of the invention read in conjunction with the appended claims and the drawings attached hereto.
The drawing, not drawn to scale, includes;
FIG. 1 which is a block diagram of an apparatus embodying the principles of the present invention;
FIG. 2 which is an end view of a bundle of optical fibers particularly adapted for use in conjunction with the apparatus shown in FIG. 1; and
FIG. 3 which is a graph showing a typical position vs. intensity plot (intensity profile) as determined by the apparatus shown in FIG. 1.
An apparatus, generally indicated at 10 in the drawing and embodying the principles of the present invention, for non-contact measurements includes a bifurcated cable 12 of optical fibers having first and second arms, 14 and 16, respectively, each arm, 14 and 16, having a first end, 18 and 20, respectively, and a common second end 22, means 24 for providing light to the first end 18 of the first arm 14, means 26 for detecting light from the first end 20 of the second arm 16, a lens assembly 28 and means 30 for introducing relative motion between the lens assembly 28 and a surface 32 to be measured. Preferably, in one preferred embodiment, the apparatus 10 further includes means 34 for controlling the apparatus 10, means 36 for recording the output of the apparatus 10, means 38 for regulating the power to the means 30 for introducing relative motion between the common second end 22 of the bifurcated cable 12 and the surface 32 to be measured, means 39 for monitoring the ambient temperature within the lens assembly 28, and means 41 for selecting the optical wavelength reaching the means 26 for detecting light.
In one particular embodiment, the bifurcated cable 12 can be any commercially available optical fiber cable that has the optical fibers thereof split into the first and second arms, 14 and 16, respectively. The arms, 14 and 16, are terminated in a conventional manner at the first ends, 18 and 20, thereof. Preferably, as shown in FIG. 2, the ends 40 of the individual optical fibers of the first arm 14 and the ends 42 of the individual optical fibers of the second arm 16 are intermixed with each other. As a result of this intermixing, as more fully discussed below, the reflections from the surface 32 to be measured are substantially equally distributed across the common end 22 of the bifurcated cable 12. Hence, the determination of the point of minimum light reflection to the means 26 for detecting light from the first end 16 is more positionally accurate than if all of the ends 40 and all of the ends 42 were adjacent each other. In one specific embodiment, each of the arms, 14 and 16, has about 800 individual optical fibers and the common second end 22 is about 2.2 millimeters in diameter.
In this preferred embodiment, the means 24 for providing light to the first end 18 of the first arm 14 of the bifurcated cable 12 includes a lamp power regulator 44 that is powered by the system control means 34, a non-coherent light source 46 powered through the power regulator 44, a lens 48 disposed in the path of light emanating from the light source 46 and a heat absorbing filter 50 disposed between the lens 48 and the first end 14 of the of the bifurcated cable 12. In one specific embodiment, the light source 46 is a halogen lamp, the lens 48 is, in this embodiment, a 5 to 1 microscope objective having a 37 millimeter working distance, a focal length of 31 millimeter, and an aperture of 0.143. The heat absorbing filter 50 absorbs heat generated from the light source 46. Alternatively, the light source 46 can be a light emitting diode.
In this embodiment, the means 26 for detecting light from the first end 20 of the second arm 16 includes a light detector 52 and a signal amplifier 54. The light detector 52 generates an electrical signal dependent upon the intensity of the light received. The light detector 52 outputs the electrical signal to the signal amplifier 54 which is connected to the control means 34. Typically, the light detector 52 is a silicon photodiode. Further, in one preferred embodiment, the means 41 for selecting the optical wavelength reaching the means 26 for detecting light is disposed between the first end 20 of the second arm 16 and the light detector 52. Preferably, the means 41 for selecting the optical wavelength includes at least one optical transmission bandpass filter. The optical transmission bandpass filter is used to maximize the reflected optical signal from the workpiece. Hence, the optical reflection wavelength resulting from such things as fingerprints on the workpiece or multiple reflections from optical coatings can be minimized.
The lens assembly 28 is a high quality transfer lens having a known focal point. Preferably, the focal point is precisely determined by measurements using a known gauge block. In this embodiment, the lens assembly 28 is sealed to prevent atmospheric disturbances from affecting the measurements and mounted to an arm member 56 of the means 30 for introducing relative motion between the lens assembly 28 and the surface 32 to be measured. In one embodiment, the movement of the arm member 56 is controlled by a stepper motor 58 controlled by the power regulator 38. Further, the means 30 for introducing relative motion between the lens assembly 28 and the surface 32, in one embodiment, includes a base member 60 rigidly affixed to a vertical member 62, or post, to which the arm member 56 is slidably mounted.
In one preferred embodiment, the means 39 for monitoring the ambient temperature within the sealed lens assembly 28 includes a conventional temperature sensor connected to the control means 34. Typically, the temperature sensor is used by the control means 34 to compensate for changes in the index of refraction of the air within the sealed lens assembly 28 due to temperature. The temperature sensor can be initialized to provide a temperature reference at start-up and thereafter provide a measurement such that the control means 34 can make compensations for the measurements taken for the effects of temperature changes.
The control means 34 can be any computerized mechanical control system including a computer adapted for use in controlling the power regulator 38, controlling the means 24 for providing light, receiving and processing signals from the means 26 for detecting light, and providing an output signal to the means 36 for recording the output of the apparatus 10.
In one specific embodiment, the means 36 for recording the output of the apparatus 10 includes a memory disk and a printer. In addition, the means 36 may also include other recording devices such as a video display, or the like.
In one exemplary operation, a spherical lens 64, the axial thickness of which is to be measured, is placed in a fixture 66 of accurately known dimensions. As the lens 48 or the surface 32 is moved with respect to the axis of the lens assembly 28 light from the first arm 14 of the bifurcated optical fiber cable 12 is reflected from the surface 32 and received through the second arm 16 and detected at the light detector 52.
The amount of light measured at the light detector 52 steadily increases as the position of the surface 32 moves with respect to the lens assembly 28. However, when the thickest point of the surface 32 of the lens 64 approaches the preset focal point of the lens assembly 28, the light reflected back to the common end point 22 is preferentially imaged onto the fibers of the first arm 14 from which it came. Consequently, the light returns to the light providing means 24 rather than going to the light detector 52. As shown in FIG. 3, this results is a dip 68 in the signal intensity. As the lens assembly 28 continues to move across the surface 32 the intensity of the signal increases again. The minimum position of the dip 68 is therefore taken as a measurement of the axial line of the lens 64.
It will be understood that a thickness measurement in absolute terms can be achieved by calibrating the apparatus 10 against an appropriate gauge block or master lens. The accuracy is then substantially determined by that of the gauge block or master lens.
In order to remove any backlash effects from the measurements, the procedure is preferably used with the lens assembly 28 always moving in the same direction.
Hence, it can be recognized that the non-contact measurement apparatus 10 is advantageous in that it can be particularly adaptable in the comparison measurements of a number of lenses. That is, once the focal point is set, a plurality of similar lenses can be measured and the acceptability of each determined.
Although the present invention has been described herein with respect to one or more particular embodiments, it will be understood that other configurations and arrangements can be made without departing from the spirit and scope of this invention. Thus, the present invention is deemed limited only by the appended claims and the reasonable interpretation thereof.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US4750835 *||Jun 21, 1985||Jun 14, 1988||Renishaw Electrical Limited||Method of and device for measuring dimensions|
|US4786176 *||Jan 6, 1987||Nov 22, 1988||Rank Taylor Hobson Limited||Metrological apparatus and method using polarization modulation|
|US5063290 *||Sep 14, 1990||Nov 5, 1991||The United States Of America As Represented By The Secretary Of The Navy||All-optical fiber faraday rotation current sensor with heterodyne detection technique|
|USRE34345 *||Sep 19, 1990||Aug 17, 1993||Dolan-Jenner Industries, Inc.||Fiber optic imaging system for on-line monitoring|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US5675406 *||Oct 17, 1995||Oct 7, 1997||Hughes Electronics||Portable device for ensuring that a center thickness of a lens is within a predetermined tolerance|
|US6014204 *||Jan 23, 1998||Jan 11, 2000||Providence Health System||Multiple diameter fiber optic device and process of using the same|
|US6043880 *||Sep 15, 1997||Mar 28, 2000||Becton Dickinson And Company||Automated optical reader for nucleic acid assays|
|US6519861 *||May 4, 2000||Feb 18, 2003||Raytheon Company||Mechanical centering apparatus and method|
|US6597450||Jan 14, 2000||Jul 22, 2003||Becton, Dickinson And Company||Automated Optical Reader for Nucleic Acid Assays|
|US6734967||Feb 11, 1999||May 11, 2004||Kla-Tencor Technologies Corporation||Focused beam spectroscopic ellipsometry method and system|
|US6776543 *||Feb 4, 2003||Aug 17, 2004||Hewlett-Packard Development Company, L.P.||Fiber optic print media thickness sensor and method|
|US6778277||May 24, 2001||Aug 17, 2004||Eastman Kodak Company||Apparatus and method to measure film motion in a film gate|
|US6870621 *||Mar 26, 2004||Mar 22, 2005||Therma-Wave, Inc.||Small spot ellipsometer|
|US7057157 *||Oct 29, 2001||Jun 6, 2006||Kirin Techno-System Corporation||Photosensor device and disk inspection apparatus using it|
|US9696328||Jul 18, 2012||Jul 4, 2017||Becton, Dickinson And Company||Automated system for isolating, amplifying and detecting a target nucleic acid sequence|
|US20020079434 *||Oct 29, 2001||Jun 27, 2002||Tb Optical Co., Ltd.||Photosensor device and disk inspection apparatus using it|
|US20030030812 *||May 24, 2001||Feb 13, 2003||Eastman Kodak Company||Apparatus and method to measure film motion in a film gate|
|US20040029260 *||May 19, 2003||Feb 12, 2004||Hansen Timothy R.||Automated system for isolating, amplifying and detecting a target nucleic acid sequence|
|US20040100632 *||Nov 18, 2003||May 27, 2004||Piwonka-Corle Timothy R.||Focused beam spectroscopic ellipsometry method and system|
|US20040179199 *||Mar 26, 2004||Sep 16, 2004||Lanhua Wei||Small spot ellipsometer|
|US20050105090 *||Dec 7, 2004||May 19, 2005||Piwonka-Corle Timothy R.||Focused beam spectroscopic ellipsometry method and system|
|US20090155808 *||Feb 11, 2009||Jun 18, 2009||Hansen Timothy R||Automated system for isolating, amplifying and detecting a target nucleic acid sequence|
|US20150097551 *||Oct 7, 2014||Apr 9, 2015||Xiaotian Steve Yao||Faraday current and temperature sensors|
|EP0769689A2 *||Oct 17, 1996||Apr 23, 1997||HE HOLDINGS, INC. dba HUGHES ELECTRONICS||A portable device for ensuring that a center thickness of a lens is within a predetermined tolerance|
|EP0769689A3 *||Oct 17, 1996||Jan 7, 1998||HE HOLDINGS, INC. dba HUGHES ELECTRONICS||A portable device for ensuring that a center thickness of a lens is within a predetermined tolerance|
|WO2013186879A1 *||Jun 13, 2012||Dec 19, 2013||Shincron Co., Ltd.||Device for measuring film thickness and device for forming film|
|U.S. Classification||356/624, 250/227.11|
|May 19, 1993||AS||Assignment|
Owner name: HUGHES AIRCRAFT COMPANY, CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:HOLLMANN, JOERG W.;REEL/FRAME:006563/0219
Effective date: 19930510
|Mar 1, 1999||AS||Assignment|
Owner name: RAYTHEON COMPANY, MASSACHUSETTS
Free format text: MERGER;ASSIGNOR:HE HOLDINGS, INC.;REEL/FRAME:009790/0503
Effective date: 19971217
|Mar 3, 1999||AS||Assignment|
Owner name: HE HOLDINGS, INC., CALIFORNIA
Free format text: CHANGE OF NAME;ASSIGNOR:HUGHES AIRCRAFT COMPANY;REEL/FRAME:009798/0610
Effective date: 19951208
|Jun 28, 1999||FPAY||Fee payment|
Year of fee payment: 4
|Jun 24, 2003||FPAY||Fee payment|
Year of fee payment: 8
|Jul 13, 2007||FPAY||Fee payment|
Year of fee payment: 12
|Jul 13, 2007||SULP||Surcharge for late payment|
Year of fee payment: 11
|Jul 16, 2007||REMI||Maintenance fee reminder mailed|
|Jan 19, 2012||AS||Assignment|
Effective date: 20120105
Owner name: RAYTHEON CANADA LIMITED, CANADA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:RAYTHEON COMPANY;REEL/FRAME:027558/0411


Scientists have found that many surfaces have distinctive spectral signatures that are apparent within certain wavelengths or channels. For instance, to distinguish between bare ground and vegetation a sensor should scan in the area between 0.6-0.7 micro-metres (red colour) and 0.7-0.9 micro-metres (near infrared). Vegetation will give a strong reflection between 0.7-0.9 micro-metres, whereas it will weakly reflect between 0.6-0.7 micro-metres.
The spectral signature of vegetation is quite characteristic so the distinction between it and bare ground is usually straightforward. The difference between radiation reflected in the visible wavelength red and near infrared can be used to determine more detail about the vegetation such as its photosynthesis and vegetated ground cover.
The Normalized Difference Vegetation Index (NDVI) is usually calculated as
|NDVI=|| near infrared - red
|near infrared + red|
Now create a NDVI image of the Alban Hills area.
Choose Tools/Compute NDVI.
Using the Alban Hills images select 'LS7_190_31_09062001_B04.tif' as the infrared band and 'LS7_190_31_09062001_B03.tif' for the red band and click OK.
Compare the image with the natural colour image and the false colour image.


The IVIS laboratory contains a variety of field resources and equipment to support the current lab projects. The resources and equipment are used to validate observations and interpretations from remote sensing data (calibration/validation) and laboratory experiments by acquiring field measurements for “ground truth”. Additionally, the field-based data are used to investigate active geologic processes for direct scientific studies.
Field-based equipment includes three multispectral forward-looking infrared (FLIR) camera systems, two larger handheld instruments (an older FLIR S40 and a new FLIR T1030sc) and a new miniature system using a FLIR A65. These camera systems accurately broadband TIR temperature data at high speeds for comparison with laboratory and orbital/airborne data products. They can be used to investigate dynamic volcanic processes (e.g., lava flow emplacement, the thermal convection and ash particle size distribution in volcanic plumes/columns), urban systems and ecological studies. The S40 and T1030sc cameras can be outfitted with telephoto optics lenses for imagine up to 5 km away from the target. In addition, the S40 and A65 have been modified with multispectral filters allowing compositional information to be derived from these cameras for the first time. These filters have a comparable spectral resolution to the ASTER, MODIS, TIIRS and VIIRS orbital sensors, which enables comparable studies to be untaken. The smaller A65 system, dubbed the miniature multispectral thermal infrared camera (MMT-Cam), is highly portable and used mostly to investigate relatively slow volcanic processes, for example, the cooling regimes of active lava lakes and lava flows. For more information about these systems please refer to the “Developing TIR field Instrumentation” page.
Additional equipment available includes an ASD Fieldspec HH VNIR field spectrometer; two Trimble differential GPS Pro systems unit with two different Laser Tech 3-D profiling systems (long and short range); a Raytek Raynger MX hand-held radiometer; and two hygrometers.
To date these field resources and equipment have been deployed on field campaigns to Arizona, Alaska, California, Hawaii, Guatemala, El Salvador, Iceland, Japan, Kamchatka and Nicaragua.


Effective 3D People Counter and Flame/Smoke Detection Cater to Vertical Applications
Huper Laboratories (known as huperLab), a leading provider of intelligent video surveillance system, and a technology innovator on 2D & 3D video analytics, showcased its mainly developed 3D People Counter and vision-based Flame/Smoke Detection at Secutech trade show in Taipei last month that caught the attention of many worldwide visitors.
Featured as great combination of surveillance and video analytics, huperVision 2D & 3D video analytics solutions can accurately detect and analyze moving objects and dynamic characteristics in real time. In addition to simply providing analytic information, video footage can also be recorded to verify details in various scenarios as forensic evidence.
Based on stereo vision, by utilizing dual-lens camera, huperLab 3D Video Analytics constructs 3D moving objects in depth to better distinguish moving objects from background, lights, shadows to achieve high accuracy. The real-time analytic information can be collected to export for further analysis in different needs. For example, the 3D analytic information can be used to distinguish adults, children and carts by specifying height filters.
Nowadays, people have been aware that early warning of flame and smoke can prevent possible tragedy and property loss. huperLab vision-based Flame/Smoke Detection solution with well-tuned CCTV/IP cameras can effectively detect and identify suspicious flame and smoke with high accuracy, and promptly send alert to the operators in seconds. It’s proved that the huperLab solution can help users take quick actions compared to conventional detectors, once they receive event notifications through mobile devices or central management system.
To increase the solution flexibility, huperLab 2D & 3D Video Analytics support SDK/CGI interfaces to integrate with the third- party products and systems, such as business intelligence analysis systems, fire/siren equipment, air-conditioning and lighting adjustment, to make their management more efficient.


SAVIMEX is specialized in optical design, and this is usually the first step in the Company’s technical offer. This activity consists of designing an optical formula based on functional specifications and integration constraints.
The Company uses CAD software for this purpose.
CODE V / ZEMAX (Modeling)
CODE V and ZEMAX are optical design softwares used to model, analyze, optimize, and provide fabrication support for the development of optical systems for diverse applications.
LightTools is a 3D optical engineering and design software product that supports virtual prototyping, simulation, optimization, and photorealistic renderings of illumination applications.


The DLR project RCAS (Railway Collision Avoidance System) aims the development, the evaluation and the demonstration of technologies for collision avoidance.
The department of optical information systems is responsible for vehicle based optical sensors within this project. It contributes to conception, test and operation of monocular and stereo cameras, its geometrical and radiometric calibration and to image data processing. The scientific goals on this area within the project are:
- Detection of switches
- Optical localisation
- Multi-sensor localisation (using additional GPS and inertial measurement units)
- 3D modelling


In the video Why all solar panels are secretly LEDs (and all LEDs are secretly solar panels) a silicon photovoltaic cell from a calculator is purposefully damaged and then a 36 V bias is applied. When imaged with a normal silicon CCD (or CMOS) camera with its infrared filter removed, infrared light can be seen emitted from the photovoltaic cell and the damage visualized.
The pattern is well delineated and instantaneous as the voltage is turned on and off, and the device is hand-held so it's not thermal infrared; cutoff for a silicon CCD is 1.1 eV or about 1100 nm.
This sounds familiar to me. I remember hearing about the use of infrared imaging to localize defects or failures in ICs a long time ago, and I think it was explained to me that the radiation was direct emission from the silicon and not just blackbody thermal emission.
Question: Am I remembering correctly? Is direct infrared photoemission from silicon used in IC manufacturing diagnostics? If so, then since silicon is not a direct band gap material, how does it produce at least small amount of light?
Note: I was reminded of this when reading the recently-posted Physics SE question Do silicon solar cells act like an LED when you flip the voltage, or are we just seeing black body radiation?


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Which lens is best for cataract surgery replacement?
A multifocal lens splits the light in each eye to give a near and distance focus. This decreases the contrast of each eye. Multifocal lenses are usually only used if they can be implanted into both eyes and are best for people who don’t have any other eye disease.
Are premium cataract lenses worth it?
Most people agree that premium IOLs are worth the extra investment. It’s important to consider if you can afford them and if living without glasses is a priority. Whatever you choose, the decision is up to you. Your eye doctor will also recommend the IOL they think is best for you.
What is the average cost of multifocal lens for cataract?
For a multifocal lens, there are extra costs ranging from $1,500 to $4,000; however, costs can fall outside of those ranges as well.
Does cataract surgery restore 20/20 Vision?
Vision Quality After Surgery
Most patients can achieve 20/20 vision as long as they have no other conditions. Conditions that can affect the quality of vision after cataract surgery include: Glaucoma. Corneal scarring.
Which lens is better monofocal or multifocal?
Existing systematic reviews have generally concluded that multifocal IOLs result in better uncorrected near vision and greater spectacle independence, but more unwanted visual phenomena such as glare and halos, compared to monofocal IOLs.
How long do cataract lenses last?
A cataract lens will last a lifetime, and the vast majority of patients do not experience any complications with their lenses after cataract surgery.
Is it OK to wear reading glasses after cataract surgery?
This sometimes happens after only one eye has had cataract surgery, and the opposite eye has a very different prescription. In this case, your old prescription glasses won’t match the newly operated eye; however, there is no harm wearing them if they help the opposite eye.
What is a premium lens?
What Are Premium Cataract Lenses? Premium cataract lenses are an upgrade from the monofocal lens that provides high-quality vision at only one focal point. However, you don’t live your life on one focal point! The premium lenses are the cherry on top of the FDA-approved laser-assisted cataract surgery we offer.
What type of intraocular lens is most popular?
One of the more popular types is the multifocal lens. A multifocal lens allows the user to see much better up close and corrects presbyopia. You also don’t need to wear glasses after cataract surgery in most instances.
Are toric cataract lenses worth it?
Excellent Toric IOL Outcomes
Research has shown that toric lenses produce excellent visual results after cataract surgery and can correct astigmatism more effectively than limbal relaxing incisions.
Which monofocal lens is best?
Fifty-four percent of the surgeons say they use the Alcon IQ Aspheric IOL for most of their cases, while 31 percent prefer the J&J Vision Tecnis one-piece lens.


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Quadralite L-60 is a projection lens that was designed specifically to work with the Quadralite optical snoot SN-5260 Pro. Combining these accesoriess allows precise illumination of the subjects both on photography as well as film sets. The f/2.8 aperture comes in handy while taking pictures in low light environment. Thanks to it, satisfactory results are possible to obtain even while using low power lights.
Small and compact design of the lens allows it to work with studio LED lights and flash units with pilot lightning switched on.
The kit includes:
- Quadralite L-60 projection lens
- Original packaging


Focusing on 3D machine vision, Cognex acquires two companies
Cognex has acquired EnShapeand complete acquisition of AQSense.
Cognex (NASDAQ: CGNX, Natick, MA) announced that it has acquired EnShape (Jena, Germany) and complete acquisition of AQSense (Girona, Spain). EnShape is a maker of 3D machine vision sensors and software based on area-scan technology for fast image capture at high resolution. The technology eliminates the need to mechanically move objects in front of the device as required with laser line scanners. The company engineers will become part of a new Cognex engineering center based in Jena.
AQSense develops and sells a library of 3D vision tools and a configuration software package that helps customers easily set up 3D vision applications. The company’s software engineers joined Cognex’s 3D engineering team upon the closing of the acquisition.
“We see a growing number of opportunities for 3D vision in industries such as automotive, consumer electronics, and logistics, to name just a few,” said Joerg Kuechen, Vice President of Vision Products for Cognex. “We believe that our acquisition of these two companies, especially the addition of two highly experienced new engineering teams, will accelerate our ability to bring innovative new 3D products to market.”


The digital revolution has reached its zenith and the stage is set for the development of Quantum Computers. Researchers have perfected a method to observe and control the spin state of a single electron with the help of Lasers.
A research team headed by University of Chicago scientists has found a way to record and manipulate the behavior of a single electron at the quantum mechanical level. The researchers used laser light in ultrafast pulses to manage the quantum state of electrons which is present inside nanoscale defects which are located in a diamond. At the center of the research is a quantum spin system also known as a nitrogen-vacancy center, an atomic-scale defect found in naturally occurring in diamonds.
Research head David Awschalom, a molecular engineering professor at Chicago said, “These defects have garnered great interest over the past decade, providing a test-bed system for developing semiconductor quantum bits as well as nanoscale sensors. Here, we were able to harness light to completely control the quantum state of this defect at extremely high speeds.”
The process envisages illuminating a single such Nitrogen Vacancy center with two pulses of light from a laser. Quantum state of the electron bound within the defect is switched on when it is excited by the first pulse and then switched off or stopped by the second pulse. The time period between the first pulse and the second pulse is important since the way electron interacts with local surroundings is determined by the timescale.
Using different timescale to test the electron’s reaction to a wide array of pulse timescale could lead to a demonstration of the quantum dynamics of an NV center, which is much better than which has been ever been obtained before.
Testing the electron’s reaction to a wide number of different pulse timescale can yield a demonstration of the quantum dynamics of an NV center that is much better than has ever been obtained before, the researchers said.
The findings have immense use in the future development of Quantum Computing. However the scientists have to move beyond just observing the quantum state controlling materials at the atomic level.


Prof. Guillermo Aguilar and his colleagues from the University of California, Riverside have developed a new approach to laser speckle imaging, called Laser Speckle Optical Flow Imaging (LSOFI) to be used for autonomous blood vessel detection and as a qualitative tool for blood flow visualization. LSOFI works by capturing the speckle displacement caused by different physical behavior and use the data to create a mapped image. It has been shown that LSOFI has many advantages over LSCI methods both in temporal and spatial resolution. Namely, LSOFI can be used to produce higher resolution images compared with the LSCI method using less frames. Combining this technology with Graphics Processing Unit (GPU) computation increases the speed of LSOFI, so GPU enabled LSOFI shows potential to create a fast and fully functional quasi-real time blood flow imaging system. Fig 1: Comparison of blood flow imaging techniques applied to the raw image. The shown results are for Laser Speckle Optical Flow Imaging (LSOFI) using the Farneback Optical Flow algorithm, traditional Laser Speckle Imaging (LSI), and Temporal Frame Averaging (sLASCA).


Dynamic range is the camera sensor’s ability to capture detail in very bright and very dark parts of a scene. Cameras (or sensors) with a low dynamic range record dark shadows as a solid black or bright highlights as a featureless white. In the days of film, this was known as a film’s ‘exposure latitude’. […]
An exposure mode on some Nikon digital cameras which balances up the exposure in high-contrast scenes. The camera reduces the exposure to make sure it captures bright highlight detail and then processes the image to brighten up dark shadows. It can be applied in different strength settings.


Benefit from our experience
In addition to our own research in the field of "optical analysis of string instruments", SCHILBACH opens its photo studio in cooperation with SCHILBACH DesignThinkingProcess for violin makers, bow makers, musicians and restorers.
Expert reports, appraisals, certificates,analysis, research or an instrument passport require photos that are as meaningful as possible and that show the instrument as true-to-proportion as possible, true to colour and in high resolution. In addition to conventional white light, photography using the LUMATEC lamps offers additional advantages.
By illuminating with different wavelengths of light, hidden objects are made visible and can be used to reinforce statements. When assessing authenticity and originality, appropriate light can provide information about the association between various components of an instrument. Photos with corresponding wavelengths show other features that can be attributed to the instrument with certainty.
We also offer photography using the invisible infrared range using an adapted camera. This can be used to illuminate opaque varnishes, to make retouched cracks on instruments and hairline cracks on bows visible or to locate worm burrows on the surface.
Photography for painting restoration
Analysis using with different wavelengths of light also offers great advantages in painting restoration. What applies to instruments also applies to a large extent to paintings.
Thus, using the short-wave UVA and violet wavelength range, retouching, polishing, colour compositions / components can be determined or, thanks to our studio, captured by a photographer. In the red spectrum, when paintings are darkened, the original image under the darkening can be made visible and easily photographed.
The invisible infrared range is suitable for the analysis of paintings, as preliminary drawings and image changes can be recorded under the top layer of paint.
Benefit from our experience in the field of professional full-format instrument photography and optical analysis.
High-resolution photos with white light and all wavelengths of the LUMATEC lamps.


Minimizing the temporal jitter in ultrafast oscillator systems is key to successful pump-probe spectroscopy. Recently, synchronization between two independent oscillators has been applied to higher-energy, amplified systems and has achieved sub-200 fs synchronization between two amplifiers.
IAN READ and KEVIN O'KEEFE
Time-resolved spectroscopic techniques are used widely by scientists for exploring processes with sub-nanosecond timescales. During the past 20 years, such techniques advanced significantly, creating an ongoing need for ever more sophisticated instrumentation. In some cases, these advances have first been defined theoretically, leaving experimentalists to anxiously await the instrumentation that enables them to explore the new territory. One such case is ultrafast laser science. From the advent of the laser in 1950, scientists have been interested in manipulating this unique light source to generate more wavelengths, more energy, and shorter pulses. Lasers can now routinely deliver picosecond (10-12) and femtosecond (10-15) pulses. Ultrafast laser science has enabled significant advances in modern chemistry, physics, and even biology1-3.
By far the most popular technique for modern time-resolved spectroscopy is pump-probe spectroscopy, which can be configured to measure transients corresponding to molecular properties (such as 2D infrared [IR] Raman), semiconductor physics (such as carrier dynamics), and materials science.4 The technique requires two optical pulses that are aligned both spatially and temporally with respect to each other. The first (pump) pulse, typically of higher energy, induces a transient effect in the sample that is then sampled by the second (probe) pulse. The time evolution of the transient is determined by methodically altering the temporal spacing between the arrival of the pump pulse and that of the interrogating probe pulse. The time resolution is determined solely by the duration of the optical probe pulse. In the simplest configuration, the pump and probe pulses are derived from the same laser pulse by splitting the beam. This single-color geometry has several advantages because using a single pulse eliminates problems arising from temporal jitter. When two lasers are required-such as for two-color experiments or when there is insufficient pulse energy from a single laser-the two lasers must be synchronized in order to minimize temporal jitter between the pulses and to optimize the overall precision of the measurement.
|FIGURE 1. Schematic representation of Spectra-Physics advanced timing configuration. Two regenerative amplifier systems are synchronized to within 200 fs. Phase adjustment of the seed oscillators can generate delays from 0 to 12.5 ns without the use of optical delay lines.|
Several techniques have been used to minimize the temporal jitter in ultrafast oscillator systems. They generally involve an electronic comparison between the optical oscillator and a reference oscillator. The difference between the oscillators is minimized by a fine cavity length adjustment of the optical oscillator so its output matches the characteristics of the reference. This method is successful in reducing temporal jitter between two independent oscillators to within 200 fs. Techniques such as coherent anti-Stokes Raman scattering (CARS) imaging have been developed using such a scheme. Many laboratories use this technique for synchronizing their experiments with free electron lasers and synchrotrons. The approach is reliable, reproducible, and affordable but has only been available for low energy oscillators. More recently, an extension of this synchronization method has been applied to higher energy, amplified laser systems.
Synchronization of ultrafast amplifiers
The classical high-energy, ultrafast laser system generally uses chirped pulse amplification (CPA) to convert ultrafast low energy (nJ) oscillator pulses to higher energy (mJ) pulses. Optical damage from the high-energy pulses is avoided by stretching the oscillator pulses before amplification. Because the extensive bandwidth content of a femtosecond pulse is large (~10-60 nm), a grating is used to stretch the pulse to several hundred picoseconds. The stretched pulse is then amplified using regenerative amplification. The high-energy picoseconds-long pulse (now several mJ) is then compressed back to its original pulsewidth.
The CPA process requires several laser sources to operate in synchrony: the seed laser, used to generate the ultrafast pulse; the amplification pump laser, used to power the amplification stage; and the amplifier. Timing of these components has traditionally been handled using an analog electronics module that controls the amplifier switches (Pockels cells). These switches and the amplification laser are synchronized while the seed laser operates in a "free-running" mode. Although operating in this manner is satisfactory for many applications, a limitation arises when high-precision measurements are required. A mismatch exists between the seed laser and amplification laser repetition frequencies so the amplifier system timing varies as a function of this mismatch. For a seed oscillator running at 80 MHz, the overall system timing uncertainty will have an upper limit of 12.5 ns. To overcome this limit, each component of the amplifier system must be synchronized. More sophisticated, digital synchronization modules such as the Spectra-Physics Timing and Delay Generator (TDG) improve precision and allow for multiple amplifier systems to be synchronized.
|FIGURE 2. Experimental setup for quasi-phase matching. Two amplifier systems operate in synchrony through use of the scheme outlined in Fig. 1. The chirped output pulse is passed through a waveplate polarizer to generate a pulse train. The characteristics of the output pulse train can be programmed using an acousto-optic programmable dispersive filter (AOPDF) to maximize harmonic generation.|
During the past few years, digital equipment has been developed for improving the overall timing capabilities of CPA laser systems. Digital electronics enable the timing of the switching electronics to be governed by the seed laser. By dividing the 80 MHz signal from the seed laser to about 1 kHz, additional amplifier systems can be synchronized to either one or multiple seed lasers to within <200 fs (see Fig. 1). When two seed lasers are used, the relative arrival of each amplifier pulse can be adjusted from t = 0 to t = tmax, where tmax is equivalent to the seed laser interpulse spacing. This adjustment is accomplished via electronic phase adjustment of the seed laser arrival time. The timing electronics (TDG1, TDG2) control the additional amplifier components. In practice, several experimental methods can be performed that benefit from this advance. A popular example of where this capability is utilized is high harmonic generation (HHG) via quasi-phase matching (QPM).
High harmonic generation
When generated using femtosecond lasers, HHG suffers from very low conversion efficiency. Typical conversion efficiencies are on the order of 10-6 for photon energies of 100 eV, with the conversion efficiency decreasing to as little as 10-15 for photon energies near 1 keV. One reason for such low conversion efficiencies is the difference between the phase velocities of the driving laser and the harmonic beam. This causes the intensity of each generated harmonic to oscillate with propagation distance. The oscillation period is 2Lc, where Lc = π/Δk. Here, Lc is the coherence length, and Δk is the wave vector mismatch. In order to overcome this problem, the harmonic generation must be phase matched such that Δk = 0. This can be achieved for output photon energies up to approximately 100 eV by balancing different sources of dispersion in a gas-filled hollow-core waveguide. However, above a certain ionization level it is no longer possible to balance the negative dispersion caused by plasma formed during ionization, and alternative approaches to phase matching are required.
Quasi-phase matching is an alternative approach suitable for increasing the generation efficiency of higher-order harmonics. The aim of QPM is to suppress HHG in those regions where the generated harmonics are out of phase with the harmonic beam. If HHG can be suppressed in N such out-of-phase regions, then the overall intensity of the harmonic beam should increase by a factor N2, greatly increasing the efficiency of this source. This increase can be achieved using a counter-propagating train of femtosecond laser pulses. In pulse-train QPM, harmonic generation is suppressed in regions where the driving laser pulse overlaps with a counter-propagating pulse. This interaction modifies the trajectory of the photoionized electron. To date, pulse trains containing just a few pulses have been used with this technique. For QPM to be most efficient, a large number of high-energy counter-propagating pulses must be generated and their relative temporal separation must be controlled.
In the simplest configuration, a single amplifier source can be used where a single, high-energy output pulse is split into two parts. The first part is used, untreated, to generate the harmonics, while the second part generates the counter-propagating pulse train. This pulse train is produced by first introducing a linear chirp onto the femtosecond pulse. The chirped pulse is then passed through a birefringent plate oriented at 45° relative to the polarization of the incident pulse. Next, a linear polarizer is oriented parallel to the incident pulse. The waveplate/polarizer combination attenuates all wavelength components whose retardance is an odd multiple of π/2; those components whose retardance is a multiple of 2π pass with no attenuation. A pulse train is formed whose spacing is constant and depends upon the thickness of the birefringent plate. An extension of this technique, in which the separation between pulses in the train can be controlled via computer, has also recently been demonstrated and is described below.5
Optimizing pulse trains for efficient HHG
This technique for generating pulse trains with variable pulse spacing is of particular interest for QPM because it enables them to be tailored to best match the coherence lengths of harmonics in a waveguide.6 The lengths can change based upon local conditions inside the waveguide. In order to achieve QPM over many coherent zones pulse trains must be generated in which there are large numbers of pulses of sufficient energy that each pulse in the train can suppress harmonic generation, and in which the spacing between the pulses can be controlled to deliver pulse trains with nonlinear pulse spacing. Programmable control of these pulse trains is a major advantage since it allows the most suitable pulse train to be easily synthesized to quasi-phase-match a particular harmonic.
The first step to achieving this level of control requires that the driving pulse and counter-propagating pulse come from two different amplifier sources and that the amplifier sources are fully synchronized (see Fig. 2). In this configuration, the driving pulse is delivered, untreated, from the first amplifier. The counter-propagating pulse originates from the second amplifier, and its characteristics are controlled using a pulse shaper. Pulse trains with variable pulse spacing can be generated and HHG via QPM can be maximized.
Synchronization of the amplifier pulses is critical for QPM in this configuration because the driving and counter-propagating pulses must collide at the same point in the waveguide for each laser shot. The Spectra-Physics Timing and Delay Generator enables a clean and robust approach for achieving sub-200 fs synchronization between two amplifiers at no additional cost.
1. A.H. Zewail, Femtochemistry: Ultrafast Dynamics of the Chemical Bond, World Scientific Series in 20th Century Chemistry, Vol. 3, World Scientific Publishing Co. Pte. Ltd., Singapore (1994).
2. Y. Silberberg, "Ultrafast Physics: Quantum Control with a Twist," Nature, 430, 624-625 (Aug. 5, 2004).
3. W. Denk, J.H. Strickler, W.W. Webb, "Two-photon laser scanning microscope," Science, 248, 73-76 (1990).
4. C. Weiman; T.W. Hänsch, Phys. Rev. Lett., 36, 1170 (1976).
5. K. O'Keefe, T. Robinson, and S.M. Hooker, "Generation and control of chirped, ultrafast pulse trains," J. Opt., 12, 015201 (2010).
6. T. Robinson, K. O'Keefe, S.M. Hooker, "Generation and control of ultrafast pulse trains for quasi-phase-matching high-harmonic generation," J. OSA B, 27, 763-772 (2010).
Ian Read is senior product manager, ultrafast amplifiers for Newport Corp.'s Spectra-Physics Laser Division, 3635 Peterson Way, Santa Clara, CA 95054; e-mail: email@example.com; www.newport.com. Kevin O'Keefe is senior research associate, Department of Physics, Clarendon Laboratory, University of Oxford, Oxford, England.
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We describe the synthesis and spectroscopic investigation of neodymium-doped silicone-urea copolymers. Absorption and luminescence analysis show that neodymium-doped silicone-urea copolymers are promising candidates for the development of polymer-based active photonic devices in the near infrared.
© 2006 Optical Society of America
U. Demirbas, A. Kurt, A. Sennaroglu, E. Yilgor, and I. Yilgor, " Luminescence Characteristics of Nd3+-Doped Silicone-Urea Copolymers," in Advanced Solid-State Photonics, Technical Digest (Optical Society of America, 2006), paper WB22.
References are not available for this paper.