Abstract: A wavefront correction system is provided which uses an achromatic null lens to correct various aberrations introduced in a spherical wavefront when the wavefront is reflected off a non-spherical surface, particularly a parabola. Chromatic aberration, including spherochromatism, is corrected over a relatively wide bandwidth. When used in conjunction with an interferometer and a variable wavelength source, the wavefront correction system provides adequate means for determining relative position errors of the segments of a segmented mirror. The derivative of the phase error is obtained with wavelength by measuring interference for different wavelengths of light. This allows position errors of greater than one half wavelength to be accurately measured.

Abstract: Doped lanthanum orthogallate laser materials produced in the form of large perovskite-type doped single crystals are disclosed. Doped single crystals of lanthanum orthogallate are grown from a pure melt of lanthanum oxide, gallium oxide and dopant oxide while controlling the major crystallographic direction of solidification. Dopants are selected from the rare earth series elements, first transition series elements and actinide series elements.

Abstract: Monocrystalline lanthanum orthogallate grown along a predetermined crystallographic direction in the form of a single crystal of a size greater than 1 cm in diameter/width and at least 10 cm in length is described. Also described is a class of perovskite type monocrystalline compositions which are readily grown from a pure melt along a predetermined crystallographic direction. Such perovskite-type monocrystalline compositions have the following formulae:LaGa.sub.1-x Sc.sub.x O.sub.3 1.LaGa.sub.1-x Al.sub.x O.sub.3 2.LaGa.sub.1-x In.sub.x O.sub.3 3.wherein x=0.001 to 0.5. Additionally described is a class of perovskite-type monocrystalline compositions of the following formula:R.sub.x La.sub.1-x GaO.sub.3wherein R is a rare earth element of smaller ionic radius than La and wherein x=0.001 to 0.5. Further described is a class of perovskite-type monocrystalline compositions of the following formulae:R.sub.x La.sub.1-x Ga.sub.1-y Al.sub.y O.sub.3R.sub.x La.sub.1-x Ga.sub.1-y Sc.sub.y O.sub.3R.sub.x La.sub.1-x Ga.

Abstract: A deformable mirror is disclosed having replaceable, electrically operable actuators for deforming the mirror's reflecting surface. A flexible retraction membrane is disposed between the actuators and the reflecting surface and the mirror's facesheet is bonded to the retraction membrane. The membrane provides constant contact between the facesheet and the mirror's actuators and provides a deflection load to mechanically drive the facesheet downward against the operation of the actuators, thus providing a mechanical force to deflect the mirror's reflecting surface when electrical signals are selectively removed from one or more of the mirror's actuators. The membrane contains a gradient stiffness in the vicinity of each actuator to tailor the deformation profile, to maintain circular symmetry and to minimize the curve fitting error in the vicinity of each actuator.

Abstract: A deformable mirror construction is disclosed in which a difference in pressure between the front reflecting surface of the deformable mirror and an enclosed chamber behind the mirror's reflecting surface is used to restore the reflecting surface to its undeformed condition after its shape has been deformed by the selective operation of one or more electrodistortive actuators. A pump is associated with the chamber to produce at least a partial vacuum in the enclosed chamber. The use of a pressure differential to influence the shape of the mirror's reflecting surface avoids the need to have the actuators fastened to the reflecting surface, thereby permitting a construction which provides for the easy replacement of actuators. A preferred embodiment of the deformable mirror includes an apparatus for circulating a coolant through the mirror's faceplate to remove heat therefrom.

Abstract: A construction for electrodisplacive transducers for use in deformable mirrors in which the transducer is assembled from two or more segments of electrodisplacive material. Each segment contains multiple stacked layers of electrodisplacive material which are separated from adjacent layers by electrodes. During manufacture the segments may be individually tested and sorted by the stroke that they produce for a given electrical input signal applied to the stacked layers. Segments are selected and fastened to each other so that the total stroke produced by the selected segments equals the stroke required from the actuator.

Abstract: An apparatus and method for calibrating deformable mirrors having replaceable actuators are disclosed. The mirror to be calibrated is mounted on an x-y table to permit selective movement of the mirror between an actuator position adjustor means and a sensor probe which senses the extent of deflection of the mirror's reflecting surface. A light source provides a source of illumination for selectively illuminating areas of the reflecting surface in the vicinity of an actuator to be adjusted. A photodetector array receives the reflected light and transmits its output to a controller which computes the distance between the sensor probe and the reflecting surface. The controller may be used to selectively energize the actuator position adjustor means to control the extent that one or more actuators influence the shape of the mirror's reflecting surface.

Abstract: A construction for a deformable mirror is disclosed in which permanent magnets are used to both retain actuators used to selectively deform the faceplate's reflecting surface within the mirror's base and to retain the mirror's faceplate to each of the actuators. The faceplate may be removed from the base by rotating each of the actuator's within its mounting hole to disrupt the magnetic circuit between each actuator and ferrous elements on the faceplate. Removal of one or more actuators from the base without disturbing the faceplate may be effected by rotation of the actuators to be removed to disconnect magnets in plugs used to support each actuator within the base from ferrous elements in the base.

Abstract: An aspheric optical test plate assembly is disclosed which permits a qualitative comparison to be made between the surface contour of a known area of an aspheric optical element and the surface contour of an area on the aspheric optical element which should be equivalent to the contour of the known area. The aspheric optical test plate assembly includes an optical test plate in the shape of a segment of a spherical element and means for stressing the element to make its contour approximate the contour of an aspheric surface.

Abstract: A short pass filter is disclosed which exhibits high transmission in the infrared and/or visible region of the electromagnetic spectrum and which has high rejection in the microwave portion of the spectrum. The filter generally consists of a substrate of semiconducting material, for example, n-type germanium which has been doped with a suitable dopant or grown with impurities to provide a substrate with a known conductivity. A metal mesh is placed either on one or on both surfaces of the substrate, or is buried within the substrate. The combination of the semiconducting material and metal mesh produce a filter which will transmit infrared and/or visible radiation while rejecting microwave radiation through absorption and reflection.

Abstract: A method is disclosed for manufacturing multilayer printed circuit boards in which one or more layers thereof, including intermediate layers, may include one or more screened on resistors. The method is particularly well suited for use where large numbers of resistors are required on one or more intermediate layers of a multilayer printed circuit board. The method includes the steps of manufacturing individual layers of the multilayer board with electrical circuits thereon and subsequently screening on one or more values of resistors using a polymer thick film resistive ink. Each layer of the multilayer board is cured to dry the polymer thick film resistors. The individual layers are thereafter bonded together into a multilayer board.

Abstract: A wavefront reconstruction and measuring system detects incoming light waves with a wavefront sensor having an array of photodetectors. The sensor provides a data processor with signals indicative of phase differences between sample points on the wavefront. The measured phase differences and respective spacing of the sample points form a matrix associated with the input wavefront. The matrix has unit cells with orthogonal sides defined by the measured phase differences and with corners defined by four commonly laterally, longitudinally or diagonally adjacent sample points. The data processor iteratively modifies each measured phase difference by a fraction of the curls of unit cells or groups of unit cells comprising the side defined by the measured phase difference. The data processor iteratively modifies each measured phase difference until the curls of each unit cell relaxes to ten percent or less of its original value.

Abstract: An adjustable mount for optical components is disclosed which permits a component held by the mount to be adjusted with six degrees of freedom. The mount includes means for locking the components of the mount to prevent vibration from affecting the adjustment of the mount while still permitting the mount to be assembled without applying excessive pressure to the mount's components, thereby permitting the position of an optical component held by the mount to be easily changed. When used to support an optical component, the mount permits the focus, tip and tilt, radial translation and rotation of the optical component relative to the brackets supporting the component to be changed without the need to cement the components of the mount into place to prevent vibration from affecting the adjustment of the components of the mount.

Abstract: An analog video signal obtained from a television camera having a 4:3 aspect ratio is converted into a square array of N.times.

Abstract: A carrier for electronic components which generate heat during their operation, such as high power semiconductors, is disclosed. The carrier includes complementary ends which are designed to permit the second end of a first carrier to abut and overlap the first end of a second carrier to conserve space when more than one carrier is mounted on a substrate containing an electronic circuit. Preferably each end of each carrier has an aperture bored therethrough to allow the carrier to be mounted to the substrate with fasteners such as screws. The apertures are located so that the aperture in the second end of a first carrier aligns with the aperture in the first end of a second carrier to permit a first and a second carrier to be fastened to the substrate with a common fastener passing through the aligned apertures. Similarly, the aperture in the second end of a second carrier is positioned to align with an aperture in the first end of another carrier.

Abstract: A method of mixing light from a signal source with light from a local oscillator for heterodyne or homodyne detection using differential detection techniques is described. In the method and apparatus of the invention, incoming light is matched to the polarization of the local oscillator no matter what the polarization of the incoming light is. A sequence of three polarization beamsplitters is utilized to achieve this match. The local oscillator signal and the incoming signal are incident on separate faces of a first polarization beamsplitter. Each is divided into two beams by that beamsplitter and paired with the orthogonally polarized component of the other, each signal/local oscillator pair exiting from one exit face of the first polarization beamsplitter. The second polarization beamsplitter resolves one of these pairs into sum and difference pairs of matched polarization which interfere and are detected by square law detectors, forming currents which are subtracted in a differential amplifier.

Abstract: A plurality of digital words representing picture elements are sequentially loaded into a readin register, which words are thereafter written in parallel into a random access memory via a write data register. The words are subsequently readout of the random access memory in parallel into a read data register and to a readout data register which thereafter sequentially transmits the words stored therein to an output circuit. The arrangement is such that each word may flow through the pipeline to be processed during a clock period of P ns; although the RAM response time is greater than P ns.

Abstract: A wavefront of light is focused upon a first shearing interferometer having a relatively large shear and small dynamic range and a relatively minor portion of the light is focused upon a second shearing interferometer having a relatively small shear but large dynamic range. Owing to the limited dynamic range of the first shearing interferometer a plurality of a plurality of virtual candidate measurements are manifest which are compared with the temporally and/or spatially averaged values of each measurement produced by the second shearing interferometer and the closest match is employed to obtain a highly accurate unambiguous reading of the wavefront slope measurements.

Abstract: A shearing interferometer produces a matrix of loops of wavefront phase difference vector signals derived from the interferogram indicative of wavefront slopes, where each loop corresponds to a sub-aperture portion of the wavefront under examination. Curl operators are applied to sum the vector signals in one direction about the loops to provide sums which are set equal adjacent loops are identified having such modified sums differing from each other by at least one integer, and in certain cases having modified sums of integers of opposite sign indicative of phase difference measurements greater than the dynamic range of the interferometer, and thus having error components therein. The phase difference values at the boundary of each of such particular identified adjacent loops are operated upon to set the modified sums to zero, to in turn eliminate the error components due to operation of the interferometer outside of the limited dynamic range.

Abstract: A frame processor for processing digitized image information includes a memory for storing a two-dimensional array of pixels, logic circuits for controlling the writing and reading of information into the memory, an arithmetic and logic unit having two inputs, one of which is coupled to the output of the memory, and a microprocessor for controlling operation of the arithmetic and logic unit and the logic circuits for controlling reading and writing.