Abstract: A focus detecting system for detecting focus state of an image forming optical system relative to an object, includes a beam splitter assembly for forming at least three coplanar two-dimensional images of a scene, each image having a different focus setting. An area array image sensor senses the images at the image forming plane. Signal processing electronics determine the sharpness of the three images and calculates an optimum focus setting for the optical system by deterring the variances of the three images and calculating a position of maximum variance corresponding to a best focus setting of the optical system.

Abstract: An optical image processor which may be used for optical image correlation comprises a liquid crystal spatial light modulator for displaying an input image as a two dimensional array of pixels. An array of photodetectors provides the output. Between the SLM and the photodetectors, there are provided a spatial light modulator and microoptic array of pin holes or lenses. The SLM has a respective picture element for each of the elements of the array and displays a filter or template image for correlation with the images displayed on the input SLM. Each photodetector of the array of output photodetectors views each of the pixels of the SLM via respective pin holes or lenses and pixels of the SLM and array. Thus, each photodetector receives light from the input through an array of pin holes or microlenses which, when selectively shuttered, act as a filter.

Abstract: A Cockcroft-Walton (CW) multiplying circuit is mounted to wrap around a cylindrical structure. A photomultiplier tube (PMT) has a photocathode which emits electrons and has dynodes connected to the CW multiplying circuit. The dynodes are biased to attract electrons from the photocathode. An electrical shield surrounds the PMT and the PMT nests within the shield. The cylindrical structure surrounds the shield and the shield nests within the cylindrical structure. The shield is a conductive material which electrically isolates the PMT from the CW multiplying circuit.

Abstract: The multiple-input OR-gate includes a set of pull down transistors connected in parallel to a common signal line. A pair of first and second inverters are connected along the common signal line between the input pull down transistors and an output. A feedback element connects an output of the second inverter to an input of the first inverter. The inverters are configured to maintain the input of the first inverter at a first intermediate voltage level of V.sub.cc -2 Vt. Input signals received by the input transistors cause the voltage on the signal line to be pulled from the first intermediate level toward Vss. The first inverter responds by generating an output signal which swings from a low voltage of V.sub.ss towards a second intermediate level of V.sub.cc -0.7 Vt. The second inverter responds by generating an output signal which swings between the high level of V.sub.cc and a low level of V.sub.ss.

Abstract: An improved photocathode (12) and image intensifier tube (10) are disclosed along with a method for making both the tube (10) and photocathode (12). The disclosed image intensifier tube (10) creates a visible light image (20) from an image emitting photons (22). The tube (10) comprises a photocathode (12) having an indium-gallium-arsenide active layer (26) and an aluminum-gallium-arsenide window layer (28). The photocathode (12) is operable to emit electrons (23) in response to the photons (22). A display apparatus is coupled to the photocathode (12) and is operable to transform the emitted electrons (23) into a visible light image (24). An embodiment of the invention is capable of detecting 1.06 .mu.m radiation.

Abstract: A highly sensitive optical fiber cavity coating removal detector employs an optical fiber 18 having a pair of Bragg gratings 20,30 embedded therein and separated by a section of fiber making up an optical cavity 26. The optical path length of the cavity 26 is sized with the central reflection wavelength of the fiber gratings 20,30 so as to create an optical resonator. The cavity 26 is coated with a material 40 which corrodes or is otherwise removable, such as aluminum. The coating 40 exerts forces 46 radially inward on the cavity 26 so as to cause the refractive index of the cavity and thus its optical path length to change, thereby causing the resonator to come out of resonance. The forces 46 on the cavity 26 are reduced when the coating 40 corrodes, thereby causing the resonator to re-enter resonance. Additionally, the coating causes optical losses to exist due to non-uniform variations in refractive index caused by non-uniform forces from coating irregularities.