In this edition, sponsored by Master Bond and Nextreme: - Light Scrambling Technique May Produce Sharper Images
- Researchers Develop Light-Treatment Device to Improve Sleep Patterns
- New on the Market: 3D Image Sensor, Plate Polarizers, Temperature Controller, Gooseneck Illuminator
| SCRAMBLED RAYS  | | Electrical engineer Jason Fleischer led a group of researchers in inventing a technique to produce sharper images and a wider field of view for medical diagnostics, microscopes and other imaging systems. (Photo: Frank Wojciechowski) |  | | An object illuminated by light reflects rays in many different directions (gray arrows). With a normal lens (shown on left) some rays are captured and refract towards a camera while other rays are missed, resulting in a blurry image with a limited field of view. The new method (shown on right) uses a nonlinear material to let the rays "talk" with each other. The original rays are altered and new rays (shown in red) are generated. The resulting picture in the camera is scrambled, but a computer algorithm can undo the mixing and yield a crisp, wide-field image. (Image: Christopher Barsi) | When photographers zoom in on an object to see it better, they lose the wide-angle perspective. In other words, they are forced to trade off "big picture" context for detail. But a new imaging method developed by Princeton University researchers could lead to lenses that show all parts of the scene at once in the same high detail. The new method could help build more powerful microscopes and other optical devices.
Cameras and other optical devices - including the human eye - are limited by the amount of light that they can collect through their lens openings, or apertures. In order for a light ray to be recorded, it has to pass through the lens and reach the device's "detector," such as the eye's retina or a digital camera's detector. But many light rays never make it to the detector, either because they are too weak, or because they are deflected. This problem is particularly acute with details that are smaller than the wavelength of light. Light rays from such tiny features fade before they reach the lens. To capture these rays, devices have to probe very near the surface of the object, and scan it point-by-point, stitching together a full image.
The new method addresses the shortcomings of small apertures by taking advantage of the unusual properties of substances called nonlinear optical materials. In conventional lens materials such as glass or plastic, rays of light pass through without interacting with one another. In nonlinear materials, light rays mix with each other in complex ways. Rays that don't reach the camera may pass along some of their information to rays that do get recorded by it. Thanks to the mixing of rays, information that would otherwise be lost manages to reach the camera. The image from a nonlinear lens would therefore be rich in detail. Unfortunately, it would also be distorted – and useless for conventional optics. But if the information could be unscrambled, a computer could reconstruct a high-resolution undistorted image of the entire scene.
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SLEEP TIGHT WITH BLUE LIGHT  | | Researchers at Rensselaer Polytechnic Institute's Lighting Research Center are developing specially designed goggles that deliver blue light spectrally tuned for optimum circadian response. |
Sleep disturbances increase as we age. Some studies report that more than fifty percent of seniors 65 years of age or older suffer from chronic sleep disturbances. One possible cause of these disturbances, according to researchers, could be a disruption of the body's circadian rhythms — biological cycles that repeat approximately every 24 hours. In recent years, scientists at Rensselaer Polytechnic Institute's Lighting Research Center and elsewhere have demonstrated that blue light is the most effective at stimulating the circadian system when combined with the appropriate light intensity, spatial distribution, timing, and duration. Using that data, a team at the Lighting Research Center (LRC) recently tested a goggle-like device designed to deliver blue light directly to the eyes to improve sleep quality in older adults.
"Light and dark patterns are the major synchronizer of circadian rhythms to the 24-hour solar day," said Mariana Figueiro, Ph.D., Lighting Research Center Light and Health Program director and principal investigator on the project. "Light stimulus travels through the retina, the light-sensitive nerve tissue lining the back wall of the eye, to reach the master clock in the brain. However, a combination of age-related changes in the eye and a more sedentary lifestyle may reduce the amount of light stimulus reaching an older person's retina, therefore reducing the amount of light for the circadian system."
As we age, the lens in the eye thickens and the pupil shrinks, reducing the amount of light passing through to the retina. In some cases, such as persons with Alzheimer's disease, the circadian system may require a stronger light stimulus due to deteriorating neural processes in the brain. These physical and neural changes can lead to muted signals to the circadian system. Factor in environmental influences, such as an indoor lifestyle with less access to daylight, and you have a perfect scenario for the development of irregular sleep-activity patterns.
A marked increase in daytime lighting levels can counteract the age-dependent losses in retinal light exposure by providing a stronger signal to the circadian system. However, the color and intensity of commercially available lighting systems, like those used in senior residences, assisted-living facilities, and nursing homes, are designed for visual effectiveness and minimal energy use rather than generating light to stimulate the older circadian system. Hence, the specially designed goggles that deliver blue light spectrally tuned for optimum circadian response.
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PRODUCT BRIEFS  | ifm efector inc. (Exton, PA) has introduced a new 3D image sensor that measures size, shape, and volume in industrial automation applications. The compact sensor uses time-of-flight distance measurement and photonic mixer device technology to identify an object in the sensor's field of view. For image capture, the 3D sensor's 64 x 48 pixel array projects 3072 points of reference, capturing the entire image in three dimensions. Each pixel within the array has two gates that are controlled by a 20MHz oscillator. Light is emitted from the sensor, reflected by the target, and received back into the PMD chip. The electrons are converted into photons and are separated into the optically sensitive area of the semiconductor called the "mobile charge carrier". Relating the phase difference measured by each pixel to the speed of light gives the distance travelled by light falling onto the detector. The phase shift of the light is then compared to the reference signal and sent from the chip as the representative distance for that pixel. Information from all the pixels is then brought together to create a 3D image.
Click here to learn more. |  | Saint-Gobain Crystals (Boulder, CO) has introduced a range of high-performance, thin-film plate polarizers optimized for use with Nd:YAG, Nd:YVO4, and Nd:YLF lasers operating at 1064 nm, 1053 nm, 532 nm, 355 nm, and 266 nm. These new Alpine Research Optics-brand optics use a first-surface coating to separate orthogonal polarizations with a high extinction ratio. They are designed to work at Brewster's angle (typically 56° angle of incidence), and can be tilt tuned (±3°) to optimize performance. These optics also feature a high transmission efficiency as well as excellent damage threshold and mechanical durability characteristics. Saint-Gobain Crystals typically provides polarizers on 28.6 mm x 14.3 mm x 3.2mm fused silica substrates. In addition to this standard product line, polarizers with custom sizes, shapes and performance characteristics over the wavelength range of 266 nm to 1550 nm can be produced upon request.
Click here to learn more. |  | The WTC3243 temperature controller from Wavelength Electronics (Bozeman, MT) has been upgraded for greater temperature stability, even across ambient. Stability is a measure of how close the actual load temperature stays to setpoint temperature over time. The linear, PI (Proportional, Integral) control loop offers maximum stability while the bipolar current source has been designed for higher efficiency. Optimized for ultrastable thermoelectric temperature control applications, the WTC3243 maintains precision temperature regulation using an adjustable sensor bias current and error amplifier circuit that operates directly with thermistors, RTDs, AD590, and LM335 type temperature sensors.
Click here to learn more. |  | The Fiber-Lite MI-150DG Illumination System from Dolan-Jenner Industries (Boxborough, MA) includes a dual gooseneck fiber optic and focusing lens, and features two points of high-intensity illumination, providing the greatest versatility for specific applications. The system's dual goosenecks can be positioned to optimize light where it is needed most, thereby offering the versatility to adapt to almost any application. Dolan-Jenner's gooseneck fiber optic assemblies are available individually, or can be purchased as a complete system with the 150 watt, MI-150DG light source, which features a lamp life of 200 hours of full intensity and up to 10,000 hours at lower intensities, a noise level less than 25dB, and a weight of just 9.25 pounds. Custom fit fiber optic ring lights are also available for the following microscopes: Nikon SMZ Series, Olympus SZ Series, Leica S4/S6/S8APO, and the Unitron ZST and ZSB.
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