Abstract: A method and sensor for determining the ratio of two components in a fluid mixture comprising a test cell in open communication with the fluid mixture and a reference cell containing a desired fluid mixture not in contact with the fluid mixture being tested, said reference and test cells having the same cell geometry. By use of a capacitance divider system, one determines the relative capacitances of said cells correlated with the dielectric constants of the respective fluid mixtures and ascertains the ratio of one component to the other component in the fluid mixture on the basis of the linear and monotonic correlation between the dielectric constant of the mixture at a given temperature and the ratio of one component to the other component. Preferably a mixture of methanol and water is tested such as for use as a feed to a reformer used in supplying hydrogen to a fuel cell. A fixed capacitor equivalent to the reference cell at a given temperature is usually substituted for the latter.

Abstract: A method and sensor for determining the ratio of two components in a fluid mixture comprising a test cell in open communication with the fluid mixture and a reference cell containing a desired fluid mixture not in contact with the fluid mixture being tested, said reference and test cells having the same cell geometry. By use of a capacitance divider system, one determines the relative capacitances of said cells correlated with the dielectric constants of the respective fluid mixtures and ascertains the ratio of one component to the other component in the fluid mixture on the basis of the linear and monotonic correlation between the dielectric constant of the mixture at a given temperature and the ratio of one component to the other component. Preferably a mixture of methanol and water is tested such as for use as a feed to a reformer used in supplying hydrogen to a fuel cell. A fixed capacitor equivalent to the reference cell at a given temperature is usually substituted for the latter.

Abstract: A liquid crystal light valve is provided with an array of photoconductive pedestals surrounded by a dielectric matrix material. Metal mirror pads are formed on top of each pedestal to form a high resolution metal matrix mirror, with each pedestal/mirror combination servicing one image pixel. The dielectric matrix forms a potential barrier between the individual photoconductive pedestals which prevents lateral charge migration between pedestals. The metal matrix mirror also shields the underlying photoconductive pedestal from photoactivation by the readout beam. The dielectric matrix material has a lower dielectric constant than the photoconductive pedestals, allowing the impedance of the photoconductive pedestals to match the impedance of the liquid crystal layer with a much thinner layer of photoconductive material than in prior LCLVs using a continuous photoconductive layer.

Abstract: An infrared (IR) radiation transducer integrates an IR detector array with a liquid crystal (LC) readout. The IR detector is preferably a pixelized bolometer array, but other detectors such as pyroelectric materials are possible. To modulate the LC in response to detected IR radiation, a modulating section is provided that includes a charge injection structure which injects electrical charge in response to the detected IR radiation, and a charge transfer structure that transfers the injected charge to the LC readout section. During its active phase the charge transfer layer is depleted of majority charge carriers, and the charge injection and transfer mechanism operates in a manner analogous to a bipolar transistor. A visible readout is obtained by directing readout light through the LC, where it is modulated in accordance with the detected IR image. The transducers are small and light weight enough to be incorporated into a pair of goggles, for which no separate cooling is required.

Abstract: An infrared (IR) simulator is disclosed in which an array of pixels is defined on an insulative substrate by resistor bridges which contact the substrate at spaced locations and are separated from the substrate, and thereby thermally insulated therefrom, between the contact locations. Semiconductor drive circuits on the substrate enable desired current flows through the resistor bridges in response to input control signals, thereby establishing the appropriate IR radiation from each of the pixels. The drive circuits and also at least some of the electrical lead lines are preferably located under the resistor bridges. A thermal reflector below each bridge shields the drive circuit and reflects radiation to enhance the IR output. The drive circuits employ sample and hold circuits which produce a substantially flicker-free operation, with the resistor bridges being impedance matched with their respective drive circuits.

Abstract: A reflective matrix mirror visible to infrared converter light valve (5) includes a liquid crystal medium (60) for spatially modulating an incident infrared beam by polarization rotation, a photosubstrate (30) for receiving an incident visible wavelength image (115) and for controlling the polarization rotation of the liquid crystal medium (60) responsively to the visible image (115), and a reflective matrix mirror (40). The reflective matrix mirror (40) is positioned between the liquid crystal medium (60) and the photosubstrate (30) and reflects the incident infrared beam (125) back through the liquid crystal medium (60) such that the infrared beam (125) passes through the liquid crystal medium twice and is polarization rotated responsively to the visible wavelength image (115). A polarizer (90) positioned exteriorly of the liquid crystal medium (60) converts the polarization rotation of the infrared beam (125) into output intensity modulation to produce an infrared image (130).

Abstract: A double Schottky diode light valve (5) includes a liquid crystal (80) for locally modulating a beam (120) by polarization rotation to produce a modulated beam (121), and a photoconductor (40) located adjacent the liquid crystal (80) for receiving and absorbing a second beam (110). The photoconductor (40) controls the polarization responsively to the optical content of the second beam (110). The photoconductor (46) includes a semiconductor substrate and a pair of Schottky diodes (60/40, 30/40) disposed on opposing sides of the substrate. The absorption of the second beam (110) by the substrate (40) produces photogenerated carriers. The pair of Schottky diodes (60/40, 30/40) maintain the substrate (40) substantially depleted of such carriers and also reflects the modulated beam back through the liquid crystal.

Abstract: A double Schottky diode light valve (5) includes a liquid crystal (80) for locally modulating a beam (120) by polarization rotation to produce a modulated beam (121), and a photoconductor (40) located adjacent the liquid crystal (80) for receiving and absorbing a second beam (110). The photoconductor (40) controls the polarization responsively to the optical content of the second beam (110). The photoconductor (46) includes a semiconductor substrate and a pair of Schottky diodes (60/40, 30/40) disposed on opposing sides of the substrate. The absorption of the second beam (110) by the substrate (40) produces photogenerated majority carriers. The pair of Schottky diodes (60/40, 30/40) maintain the substrate (40) substantially depleted of such carriers and also reflects the modulated beam back through the liquid crystal.

Abstract: An LCLV is formed with a sapphire substrate base, a highly doped, thin silicon epitaxial layer forming an ohmic back contact on a smooth surface of the sapphire substrate, and a lightly doped, high resistivity silicon epitaxial layer in the range of about 20-60 microns thick on the back contact. The use of a sapphire substrate provides a better surface quality and higher resolution than previously available with the semiconductor substrates. Lattice defects in the thin back contact are reduced by the formation of a buried amorphous layer adjacent the sapphire substrate, and subsequent recrystallization thereof using the unamorphized portions of the back contact as recrystallization seeds. The application of the invention to both MOS and Schottky diode LCLVs is discussed.

Abstract: A pulsed readout technique is described for liquid crystal light valves which eliminates the problem of readout beam leakage through the light valve mirror. The readout beam is pulsed on only when the light valve's semiconductor layer is out of a depletion state. This can occur during an accumulation state or, in certain applications, during a specially inserted quiescent period in the light valve voltage cycle. The invention is applicable to light valves with various types of modulating inputs, and can be used with either dielectric or metal matrix mirrors.

Abstract: There is disclosed a single crystal silicon charge storage apparatus suitable for use in an alternating current driven liquid crystal light valve having therein a moderately doped microchannel stop grid. The charge storage medium is made of a high resistivity substrate on which an MOS capacitor is formed having fast photoelectric transient response and capable of operating over a wide frequency range. A doped microgrid structure is formed in one side of the substrate to prevent charge carrier spreading at the silicon-silicon dioxide interface and to provide a focusing electric field for the charge carriers. The signal from the substrate is electrically coupled through high-reflectivity mirrors and light blocking layers to the liquid crystal.

Abstract: A liquid crystal light valve having an improved counterelectrode structure. The light valve includes a layer of liquid crystal material which lies intermediate a photosensitive substrate of intrinsic semiconductive material and the counterelectrode. The upper surface of the substrate is characterized by a highly doped peripheral channel stop. The counterelectrode comprises electrically insulated inner and outer regions, the inner region substantially overlying only the intrinsic material interior said highly doped peripheral channel stop so that an electrical bias may be selectively applied, greatly enhancing the dark current breakdown voltage of the device.

Abstract: There is herein described a device useful to store a frame of low-intensity optical information over a wide spectral range or useful as a real-time light valve in visible to infrared conveter application. The device basically includes either a storage mode liquid crystal or a dynamic scattering or a field-effect liquid crystal, and a semiconductor diode array substrate wherein an insulating film with an array of conducting windows separates the liquid crystal from an active region in the substrate. A separate diffused junction is disposed in the active region adjacent each of the windows, the latter being adapted to both reflect incident light energy and conduct electrical current.

Abstract: This invention is directed to a semiconductor structure that includes at least one wafer that is fully depleted of all mobile carriers and is used as a medium for the movement of spatially modulated signal represented by charge carriers through the wafer with a spatial resolution that is smaller than the thickness of the wafer. This may be used in the form of a continuous high resolution silicon photodiode substrate to serve as an image input means for an electro-optical display medium, such as a liquid crystal. Next to the photoactivated substrate is a liquid crystal and next to the crystal is a transparent electrode. The photodiode is reverse biased and both of its sides are depleted of all mobile charges throughout its entire thickness. Thus, charges generated in the substrate move to the display not by diffusion as in prior art devices (e.g.

Abstract: There is disclosed a single crystal silicon charge storage apparatus suitable for use in an alternating current driven liquid crystal light valve having therein a PIN photodiode structure. The charge storage medium is made of a high resistivity substrate on which an MOS capacitor is formed having fast photoelectric transient response an capable of operating over a wide frequency range. A PIN photodiode structure is provided on one side of the substrate next to the MOS capacitor to deplete the substrate of its mobile charge carriers during a portion of the AC cycle and to collect the electric field-guided signal representing charge carriers that are generated or introduced into the substrate by an input mechanism. The signal from the substrate is electrically coupled through high-reflectivity mirrors and light blocking layers to the liquid crystal.

Abstract: There is disclosed a single crystal silicon charge storage apparatus suitable for use in an alternating current driven liquid crystal light valve. The charge storage medium is made of a high resistivity and photosensitive under AC excitation substrate on which an MOS capacitor is formed having fast photoelectric transient response and capable of operating over a wide frequency range. The AC activation provides to a liquid crystal light valve a greatly improved electrochemical stability. Electrically coupled high-reflectivity mirrors and light blocking layers can be used to couple the liquid crystal to the MOS capacitor.

Abstract: A buried channel to surface channel charge coupled device includes a blocking gate and a transfer gate situated between a buried channel gate and a surface gate for transferring electron charge from the buried channel to the surface channel. The blocking gate is located over the buried channel and the transfer gate straddles the buried and surface channels. The blocking gate serves to overcome the potential barrier associated with buried to surface channel transfers.

Abstract: There is disclosed an anisotropically conductive interface comprising a plurality of cermet and dielectric layers for use in electro-optical devices to separate a substrate driver from an electro-optical display medium to prevent display light from affecting the driver. The substrate may be a photosensor, a charge coupled device or other matrix addressing circuitry arrangement. In general the substrate is one which can provide spatially modulated voltage and/or current patterns. The display medium may be a liquid crystal, an electro-chromic, an electro-luminescent material or the like. The interface provides direct current conductivity through the interface, insulative maintenance of the spatial modulation of the signal across the interface, light reflectivity, and high attenuation of transmitted light.

Abstract: There is disclosed a silver doped silicon single crystal charge storage photodiode substrate suitable for use in an alternating current driven liquid crystal light valve. The gain capability of the charge storage photodiode makes it possible to construct a single crystal substrate ac light valve very similar in structure to that presently being used with a cadmium sulphide photodiode, but having improved operating characteristics and benefitting from a more fully developed manufacturing technology for silicon devices. One specific embodiment of such a single crystal substrate is a silicon substrate doped with a slow recombination center element such as silver.

Abstract: A single-Schottky liquid crystal is disclosed in which a series of Schottky contacts are made on one side of a photoconductor substrate by a metal matrix mirror, with a doped semiconductor back contact electrode on the other side of the substrate. The light valve offers several operational advantages over MOS devices, and is easier to fabricate than double-Schottky light valves. It can be operated either in an AC mode or, by doping the liquid crystal ions, in a DC mode.