Abstract: A method for producing a photostable reactive mesogen alignment layer includes infusing an anisotropic dye into a microcavity so as to coat the an surface of the microcavity with the anisotropic dye; illuminating the anisotropic dye with polarized light so as to form an anisotropic dye layer aligned with respect to the inner surface of the microcavity; infusing a reactive mesogen and the liquid crystal material into the microcavity; illuminating the reactive mesogen at a wavelength selected to cause polymerization of the layer of the reactive mesogen so as to form a polymerized reactive mesogen layer; aligning the liquid crystal material with respect to the anisotropic dye layer; and bleaching the anisotropic dye layer.

Abstract: Liquid crystal photonic devices and microcavities filled with liquid crystal materials are becoming increasingly popular. These devices often present a challenge when it comes to creating a robust alignment layer in pre-assembled cells. Previous research on photo-definable alignment layers has shown that they have limited stability, particularly against subsequent light exposure. A method of infusing a dye into a microcavity to produce an effective photo-definable alignment layer is described, along with a method of utilizing a pre-polymer infused into the microcavity mixed with the liquid crystal to provide photostability. In this method, the polymer layer, formed under optical irradiation of liquid crystal cells, is effectively localized to a thin region near the substrate surface and thus provides a significant improvement in the photostability of the liquid crystal alignment.

Abstract: Liquid crystal photonic devices and microcavities filled with liquid crystal materials are becoming increasingly popular. These devices often present a challenge when it comes to creating a robust alignment layer in pre-assembled cells. Previous research on photo-definable alignment layers has shown that they have limited stability, particularly against subsequent light exposure. A method of infusing a dye into a microcavity to produce an effective photo-definable alignment layer is described, along with a method of utilizing a pre-polymer infused into the microcavity mixed with the liquid crystal to provide photostability. In this method, the polymer layer, formed under optical irradiation of liquid crystal cells, is effectively localized to a thin region near the substrate surface and thus provides a significant improvement in the photostability of the liquid crystal alignment.

Abstract: The high-pixel-count uncooled thermal imaging arrays disclosed herein have liquid crystal (LC) microcavity transducers separate from the read-out integrated circuit (ROIC). The transducer converts incident infrared (IR) radiation in birefringence changes that can be measured with visible light. In other words, the system uses the temperature sensitivity of the LC birefringence to convert the IR scene to a visible image. Measurements on sample arrays indicate that the LC material quality is similar to that of bulk samples and has good noise performance. Additionally, high-fill-factor arrays on fused-silica substrates may be processed to enable optimization of conditions for greatly improved temperature sensitivity. An additional IR absorber layer may be integrated into the process to tune the structure for the infrared.

Abstract: The high-pixel-count uncooled thermal imaging arrays disclosed herein have liquid crystal (LC) microcavity transducers separate from the read-out integrated circuit (ROIC). The transducer converts incident infrared (IR) radiation in birefringence changes that can be measured with visible light. In other words, the system uses the temperature sensitivity of the LC birefringence to convert the IR scene to a visible image. Measurements on sample arrays indicate that the LC material quality is similar to that of bulk samples and has good noise performance. Additionally, high-fill-factor arrays on fused-silica substrates may be processed to enable optimization of conditions for greatly improved temperature sensitivity. An additional IR absorber layer may be integrated into the process to tune the structure for the infrared.

Abstract: Liquid crystal photonic devices and microcavities filled with liquid crystal materials are becoming increasingly popular. These devices often present a challenge when it comes to creating a robust alignment layer in pre-assembled cells. Previous research on photo-definable alignment layers has shown that they have limited stability, particularly against subsequent light exposure. A method of infusing a dye into a microcavity to produce an effective photo-definable alignment layer is described, along with a method of utilizing a pre-polymer infused into the microcavity mixed with the liquid crystal to provide photostability. In this method, the polymer layer, formed under optical irradiation of liquid crystal cells, is effectively localized to a thin region near the substrate surface and thus provides a significant improvement in the photostability of the liquid crystal alignment.

Abstract: The high-pixel-count uncooled thermal imaging arrays disclosed herein have liquid crystal (LC) microcavity transducers separate from the read-out integrated circuit (ROIC). The transducer converts incident infrared (IR) radiation in birefringence changes that can be measured with visible light. In other words, the system uses the temperature sensitivity of the LC birefringence to convert the IR scene to a visible image. Measurements on sample arrays indicate that the LC material quality is similar to that of bulk samples and has good noise performance. Additionally, high-fill-factor arrays on fused-silica substrates may be processed to enable optimization of conditions for greatly improved temperature sensitivity. An additional IR absorber layer may be integrated into the process to tune the structure for the infrared.

Abstract: Embodiments of the present invention include an electron counter with a charge-coupled device (CCD) register configured to transfer electrons to a Geiger-mode avalanche diode (GM-AD) array operably coupled to the output of the CCD register. At high charge levels, a nondestructive amplifier senses the charge at the CCD register output to provide an analog indication of the charge. At low charge levels, noiseless charge splitters or meters divide the charge into single-electron packets, each of which is detected by a GM-AD that provides a digital output indicating whether an electron is present. Example electron counters are particularly well suited for counting photoelectrons generated by large-format, high-speed imaging arrays because they operate with high dynamic range and high sensitivity. As a result, they can be used to image scenes over a wide range of light levels.

Abstract: Embodiments of the present invention include complementary metal-oxide-semiconductor (CMOS) readout architectures for photon-counting arrays with a photon-counting detector, a digital counter, and an overflow bit in each of the sensing elements in the array. Typically, the photon-counting detector is a Geiger-mode avalanche photodiode (APD) that emits brief pulses every time it detects a photon. The pulse increments the digital counters, which, in turn, sets the overflow bit once it reaches a given count. A rolling readout system operably coupled to each sensing element polls the overflow bit, and, if the overflow bit is high, initiates a data transfer from the overflow bit to a frame store. Compared to other photo-counting imagers, photon-counting imagers with counters and overflow bits operate with decreased transfer bandwidth, high dynamic range, and fine spatial resolution.

Abstract: Embodiments of the present invention include an electron counter with a charge-coupled device (CCD) register configured to transfer electrons to a Geiger-mode avalanche diode (GM-AD) array operably coupled to the output of the CCD register. At high charge levels, a nondestructive amplifier senses the charge at the CCD register output to provide an analog indication of the charge. At low charge levels, noiseless charge splitters or meters divide the charge into single-electron packets, each of which is detected by a GM-AD that provides a digital output indicating whether an electron is present. Example electron counters are particularly well suited for counting photoelectrons generated by large-format, high-speed imaging arrays because they operate with high dynamic range and high sensitivity. As a result, they can be used to image scenes over a wide range of light levels.

Abstract: The imager includes a lens for focusing infrared light forming a thermal image onto a liquid crystal array thereby changing the temperature of the liquid crystals to alter a physical property of the liquid crystals. A source of visible polarized light is arranged to illuminate the liquid crystal array so that the polarization of light reflected from the liquid crystal array varies with changes in temperature of the liquid crystals. A cross polarizer receives and transmits therethrough the light reflected from the liquid crystal array, the cross polarizer adapted to change the intensity of the light. An imager receives and detects the change in intensity of the light from the cross polarizer so that the thermal image is recreated as an electronic signal. In a preferred embodiment, the physical property is index of refraction and the liquid crystal array includes birefringent nematic liquid crystals.

Abstract: A photodiode is provided by the invention, including an n-type active region and a p-type active region. A first one of the n-type and p-type active regions is disposed in a semiconductor substrate at a first substrate surface. A second one of the n-type and p-type active regions includes a high-field zone disposed beneath the first one of the active regions at a first depth in the substrate, a mid-field zone disposed laterally outward of the first active region at a second depth in the substrate greater than the first depth, and a step zone connecting the high-field zone and the mid-field zone in the substrate.

Abstract: Embodiments of the present invention include complementary metal-oxide-semiconductor (CMOS) readout architectures for photon-counting arrays with a photon-counting detector, a digital counter, and an overflow bit in each of the sensing elements in the array. Typically, the photon-counting detector is a Geiger-mode avalanche photodiode (APD) that emits brief pulses every time it detects a photon. The pulse increments the digital counters, which, in turn, sets the overflow bit once it reaches a given count. A rolling readout system operably coupled to each sensing element polls the overflow bit, and, if the overflow bit is high, initiates a data transfer from the overflow bit to a frame store. Compared to other photo-counting imagers, photon-counting imagers with counters and overflow bits operate with decreased transfer bandwidth, high dynamic range, and fine spatial resolution.

Abstract: Embodiments of the present invention include an electron counter with a charge-coupled device (CCD) register configured to transfer electrons to a Geiger-mode avalanche diode (GM-AD) array operably coupled to the output of the CCD register. At high charge levels, a nondestructive amplifier senses the charge at the CCD register output to provide an analog indication of the charge. At low charge levels, noiseless charge splitters or meters divide the charge into single-electron packets, each of which is detected by a GM-AD that provides a digital output indicating whether an electron is present. Example electron counters are particularly well suited for counting photoelectrons generated by large-format, high-speed imaging arrays because they operate with high dynamic range and high sensitivity. As a result, they can be used to image scenes over a wide range of light levels.

Abstract: A particle detection system that images and detects particles in a fluid flow stream through use of detector array(s) is described. The detection system may include light source arrays that may selectively illuminate a particle in a fluid stream. The detection system may also include a detector array employing smart binning to read the measured signals. The smart binning of the detector array may be achieved through knowledge of an exact particle location provided by a position sensitive detector. The detector array(s) may be low cost based on intelligence built into the system. This particle detection system may be particularly useful for detection and discrimination of different particle types since the read-out of the particle signals can be accomplished with low noise and can be flexible enough to optimize the read out measurements for each particle. The particle detection system may be used, for example, in early warning contamination detection systems and manufacturing processes.

Abstract: A photon-counting Geiger-mode avalanche photodiode intensity imaging array includes an array of pixels, each having an avalanche photodiode. A pixel senses an avalanche event and stores, in response to the sensed avalanche event, a single bit digital value therein. An array of accumulators are provided such that each accumulator is associated with a pixel. A row decoder circuit addresses a pixel row within the array of pixels. A bit sensing circuit converts a precharged capacitance into a digital value during read operations.

Abstract: A particle detection system that images and detects particles in a fluid flow stream through use of detector array(s) is described. The detection system may include light source arrays that may selectively illuminate a particle in a fluid stream. The detection system may also include a detector array employing smart binning to read the measured signals. The smart binning of the detector array may be achieved through knowledge of an exact particle location provided by a position sensitive detector. The detector array(s) may be low cost based on intelligence built into the system. This particle detection system may be particularly useful for detection and discrimination of different particle types since the read-out of the particle signals can be accomplished with low noise and can be flexible enough to optimize the read out measurements for each particle. The particle detection system may be used, for example, in early warning contamination detection systems and manufacturing processes.

Abstract: A large format imager includes an array of pixels for converting electromagnetic radiation into electrical signals and a trigger to from an optical pulse so as to trigger the pixels to generate an integration period. Each pixel includes a photodiode to convert light intensity of high-frequency radiation into an electrical charge, a reset switch to reset the photodiode, circuitry to enable sampling of the electrical charge produced by the photodiode, a photoswitch to convert an optical trigger pulse, received from the trigger, into an electrical signal, an inverter to produce a control signal corresponding to the electrical signal produced by the photoswitch, and control circuitry to locally generate integration control signals. The integration control signals control a start of an integration period for the photodiode, duration of the integration period for the photodiode, and the sampling of the electrical charge produced by the photodiode.

Abstract: The CCD image sensor addresses the problem of noise, due to background charge generated by Compton scattering of gamma rays. In applications, in which an imager must operate in a high-radiation environment, such background noise reduces the video signal/noise. This imager reduces the amount of charge collected from Compton events, while giving up very little sensitivity to photons in the visible/near IR.

Abstract: A charge-coupled device imager including an array of super pixels disposed in a semiconductor substrate having a surface that is accessible to incident illumination. For each super pixel there is provided a plurality of subpixels which each correspond to one in the sequence of image frames. Each subpixel includes a doped photogenerated charge collection channel region opposite the illumination-accessible substrate surface, a charge collection channel region control electrode, doped charge drain regions adjacent to the channel region, a charge drain region control electrode, and a doped charge collection control region. To each subpixel are provided channel region and drain region control voltage connections, for independent collection and storage of photogenerated charge from the substrate at the charge collection channel region of a selected subpixel during one in the sequence of image frames and for drainage of photogenerated charge from the substrate to a drain region.