Photonics/Optics

Optical Fiber for Solar Cells

These materials enable new solar-powered devices that are small, lightweight, and can be used without connection to existing electrical grids. Ames Research Center, Moffett Field, California Polymeric and inorganic semiconductors offer relatively high quantum efficiencies, and are much less expensive and versatile to fabricate than non-amorphous silicon wafers. An optical fiber and cladding can be designed and fabricated to confine light for transport within ultraviolet and near-infrared media, using evanescent waves, and to transmit visible wavelength light for direct lighting.

Posted in: Briefs, Energy Storage, Solar Power, Fiber Optics

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Fabrication of Single-Mode, Distributed-Feedback, Interband Cascade Lasers

Applications exist in the oil and gas industry, automobile emissions monitors, breath analyzers, and fire detection equipment. NASA’s Jet Propulsion Laboratory, Pasadena, California Type-II interband cascade lasers (ICLs) based on the GaSb material system represent an enabling technology for laser absorption spectroscopy in the 3-to-5-μm wavelength range. Instruments operating in this spectral regime can precisely match strong absorption lines of several gas molecules of interest in atmospheric science and environmental monitoring, specifically methane, ethane, other alkanes, and inorganic gases. Compared with non-semiconductor-based laser technologies, ICLs can be made more compact and power efficient, ultimately leading to more portable, robust, and manufacturable spectroscopy instruments.

Posted in: Briefs, Lasers & Laser Systems, Optics, Photonics

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Algorithm for Estimating PRC Wavefront Errors from Shack-Hartmann Camera Images

Phase retrieval is used for the calibration and the fine-alignment of an optical system. NASA’s Jet Propulsion Laboratory, Pasadena, California Phase retrieval (PR) and Shack-Hartmann Sensor (SHS) are the two preferred methods of image-based wavefront sensing widely used in various optical testbeds, adaptive optical systems, and ground- and space-based telescopes. They are used to recover the phase information of an optical system from defocused point source images (PR) and focused point source or extended scene images (SHS). For example, the Terrestrial Planet Finder Coronagraph’s (TPF-C’s) High-Contrast Imaging Testbed (HCIT) uses a PR camera (PRC) to estimate, and subsequently correct, the phase error at the exit pupil of this optical system. Several other test-beds at JPL were, and will be, equipped with both a PRC and a Shack-Hartmann camera (SHC).

Posted in: Briefs, TSP, Cameras, Optics, Sensors

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Photo-Thermo-Refractive Glass Co-Doped with Luminescent Agents for All-Solid-State Microchip Lasers

Goddard Space Flight Center, Greenbelt, Maryland A proposed solid-state technology possesses photosensitivity that enables volume hologram recording and a high efficiency of luminescence, enabling stimulated emission. These features were used to record volume Bragg gratings and to demonstrate lasing under laser diode pumping for the same volume of glass. Moreover, a combination of dopants provides extremely wide luminescence bands, which enables both wideband optical processing and extremely short laser pulse generation. It is important that the whole design be incorporated in a single, monolithic piece of glass that excludes the opportunity for misalignment and sensitivity to vibrations. If developed, the compactness and reliability of such laser devices would find wide use in space or aeronautical applications.

Posted in: Briefs, TSP, Lasers & Laser Systems, Optics

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Large Computer-Generated Hologram with Software-Generated Calibration Wavefront Map

This type of testing aspheric surfaces provides better imaging, lower mapping distortion, and much higher-quality substrates. Marshall Space Flight Center, Alabama This technology enables accurate calibration of a large Computer Generated Hologram (CGH) fabricated without great accuracy, such that the CGH still measures an aspheric surface to an excellent accuracy of a couple of nm rms. The goal is the creation of software for generating a calibration map, and the fabrication of a couple of 9-in. (≈22.5-cm)-diameter CGHs to experimentally verify the technology. Use of CGHs in testing aspheric surfaces provides many advantages, such as better imaging, lower mapping distortion, and much higher-quality substrates.

Posted in: Briefs, Optics, Electronics & Computers

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Active Layer Optimization in Ultra-Thin, Surface-Parallel, Deformable Mirrors

This method enables low-cost, lightweight, active mirrors with a large dynamic range and improved actuation characteristics. NASA’s Jet Propulsion Laboratory, Pasadena, California A design methodology was developed that optimizes the performance of active mirrors. Patterns of parameterized ellipsoidal actuators are overlaid onto the mirror, and then numerically optimized to improve performance of the mirror in optical modes that are typically difficult to correct, while also improving performance in other optical modes.

Posted in: Articles, Briefs, Tech Briefs, Optics, Photonics

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Monolithic Dual Telescope for Compact Biaxial Lidar

Goddard Space Flight Center, Greenbelt, Maryland A document discusses the Ultra Compact Cloud Physics Lidar, a biaxial lidar with a narrow receiver field of view. It requires tight optical alignment between the transmitter and receiver paths while flying on various aircraft over various temperatures and in the presence of vibration. To achieve optical crossover as close to the lidar as possible, the transmit and receive telescopes must be built very closely to each other.

Posted in: Articles, Briefs, TSP, Tech Briefs, Photonics

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