Photonics/Optics

Designing 3D Capabilities Into Handheld Displays

For 3D viewing to be convenient on small, portable devices, it must be autostereoscopic, thus eliminating the requirement for 3D “glasses.” The display devices must also provide 2D and 3D capability simultaneously, without sacrificing resolution or color vibrancy.

Posted in: Application Briefs, Applications, ptb catchall, Photonics

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Solar Rejection Filter for Large Telescopes

Filters help avoid thermal loading of the receiver by incident sunlight. NASA’s Jet Propulsion Laboratory, Pasadena, California To reject solar radiation photons at the front aperture for large telescopes, a mosaic of large transmission mode filters is placed in front of the telescope or at the aperture of the dome. Filtering options for effective rejection of sunlight include a smaller filter down-path near the focus of the telescope, and a large-diameter filter located in the front of the main aperture. Two types of large filters are viable: reflectance mode and transmittance mode.

Posted in: Photonics, Briefs, ptb catchall, Tech Briefs, Photonics

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Free-Space Optical Interconnect Employing VCSEL Diodes

These optical interconnects are applicable for large-capacity interconnection between information-processing equipment. John H. Glenn Research Center, Cleveland, Ohio Sensor signal processing is widely used on aircraft and spacecraft. The scheme employs multiple input/output nodes for data acquisition and CPU (central processing unit) nodes for data processing. To connect 110 nodes and CPU nodes, scalable interconnections such as backplanes are desired because the number of nodes depends on requirements of each mission. An optical backplane consisting of vertical-cavity surface-emitting lasers (VCSELs), VCSEL drivers, photodetectors, and transimpedance amplifiers is the preferred approach since it can handle several hundred megabits per second data throughput. Conventional electrical interconnects severely limit the performance of high-speed networks because of parasitic resistance and capacitance, which limit bandwidth and cause clock signals to skew. Moreover, they cause pin congestion and require large and bulky multi-pin connectors.

Posted in: Photonics, Briefs, ptb catchall, Tech Briefs, Photonics

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Critical Coupling Between Optical Fibers and WGM Resonators

Recipes address issues of phase matching, aperture matching, and suppressing intermodal coupling. NASA’s Jet Propulsion Laboratory, Pasadena, California Two recipes for ensuring critical coupling between a single-mode optical fiber and a whispering-gallery-mode (WGM) optical resonator have been devised. The recipes provide for phase matching and aperture matching, both of which are necessary for efficient coupling. There is also a provision for suppressing intermodal coupling, which is detrimental because it drains energy from desired modes into undesired ones.

Posted in: Photonics, Briefs, ptb catchall, Tech Briefs, Photonics

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Designing Electro-Optical Sensors Using Collaborative Systems Engineering Technology

About 25% of space-borne electro-optical (EO) sensor programs in both the civil and National Security Space (NSS) communities have experienced reduced on-orbit reliability, as well as cost and schedule overruns of 100% or more1-3. Many of these EO sensor program over-runs can be largely attributed to delays, errors, and inadequate communication that occur at the many handoff points between team members and contractors in the current design process. This leads to the late discovery of technical problems, making them more expensive and time-consuming to fix.

Posted in: Articles, Features, ptb catchall, Photonics

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Choosing Optics for Medical Lasers

Designers of medical equipment using lasers must be careful in their selection of optical components in order to ensure safe and reliable operation. The high power density and narrow wavelength range of lasers create problems not found in other medical optics such as microscopes and cameras. Proper selection of materials, manufacturing specifications, and coatings becomes essential to avoid such problems.

Posted in: Application Briefs, Applications, ptb catchall, Photonics

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Instruments for Imaging From Far to Near

These instruments could also perform some spectral imaging functions at close range. NASA’s Jet Propulsion Laboratory, Pasadena, California The acronym “CHAMP” (signifying “camera, hand lens, and microscope”) denotes any of several proposed optoelectronic instruments that would be capable of color imaging at working distances that could be varied continuously through a range from infinity down to several millimeters. As in any optical instrument, the magnification, depth of field, and spatial resolution would vary with the working distance. For example, in one CHAMP version, at a working distance of 2.5 m, the instrument would function as an electronic camera with a magnification of 1/100, whereas at a working distance of 7 mm, the instrument would function as a microscope/electronic camera with a magnification of 4.4. Moreover, as described below, when operating at or near the shortest-working-distance/ highest-magnification combination, a CHAMP could be made to perform one or more spectral imaging functions.

Posted in: Photonics, Briefs, ptb catchall, Tech Briefs, Photonics

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