Abstract: A laser system for measuring dimensional aberrations across a target surface includes a laser diode for producing a diverging beam of laser emission. A mask spaced from the diode in the beam has an aperture therein and can be moved so as to translate the aperture to selected locations laterally with respect to the beam. The mask blocks emission from impinging on the target except for emission transitting the aperture. Emission reflected from a segment to the target returns through the aperture back into the laser diode. An AC current is added to the driver current to modulate the emission. A lock-in amplifier of a photodetector signal adds feedback current to the driver current to lock in phase angle, so that the feedback current is a measure of the aberrations.

Abstract: A charge-coupled imaging device (FIG. 3) is thinned to allow for backside illumination. The device is further enhanced using ion implantation techniques to establish an electrical field (44) at the back surface, which functions to drive free electrons to potential wells generated beneath a gate structure (40) on the front surface. The device structure allows for both front side and backside illumination and is useful as an imaging device in applications where it is necessary to combine images from two different optical sources. The imaging device is particularly useful in terrestrial guidance systems (FIG. 5) where the imaging device is used to detect guide stars from a large guide star field. In such systems, the imaging device must be translated within an X-Y plane in order to cover the entire guide star field. In order to accurately know the position of the imaging device, optical fiducial marks are imaged onto a side of the imaging device opposite the side receiving the guide star photons.

Abstract: Optical interconnectors and methods for optically interconnecting structures, such as printed circuit boards. The optical interconnectors comprise at least two optical fibers having one end embedded in a structure such as a printed circuit board and at least one sleeve for housing termination portions of two optical fibers. The termination portions of the fibers are positioned and secured within the sleeve so that end surfaces of the optical fibers are abutted together. The resulting optical interconnectors have low loss and occupy a small amount of space while maintaining a flat profile.

Abstract: A pair of anvils (50,54) are respectively fixed to and movable with respect to a base (12). Each anvil has a surface (52,56) of given topography, preferably a flat surface. The surfaces are spaced in parallel from one another at an initial gap so that the anvil surfaces do not contact one another. The movable anvil (50) can be moved away from the fixed anvil (54), such as by a cam (44) and follower (38), and the surfaces are maintained in parallel preferably by a parallelogram constant force flexure assembly (26). The cam is set to maintain a minimum space between the surfaces and to protect them from damage, in the event the movable anvil were accidently dropped towards the non-movable anvil. Parallelism between the surfaces is initially established preferably by an adjustment mechanism comprising a trivet/turnbuckle assembly (58). A displacement transducer (22) is coupled to the movable anvil for measuring the gap as determined by the thickness of a gage or product placed between the surfaces of the anvils.

Abstract: The phase ambiguity of conventional interferometers may be removed by using two laser diodes of different optical frequency to generate a synthetic wavelength. However, the stability requirements for a two-color interferometric laser gauge that must provide unambiguous determination of the optical fringe order over a large distance can be severe. The invention determines upper limits on the optical wavelength uncertainity and expresses same as a function of optical path difference between object and reference beams, phase measurement errors and the synthetic wavelength. A wavelength stabilization arrangement involves simultaneous servo control of two laser diodes (10, 12) with a single Fabry-Perot etalon (36). An embodiment of the invention demonstrates its effectiveness for long-term stabilized two-color interferometry over a distance of 250 mm, with a 15 .mu.m synthetic wavelength and a repeatability of 40 nm. For periods of less than 1000 seconds, the repeatability is eight nm.

Abstract: Techniques for calibrating differential temperature sources including the use of a calibrated infrared imaging sensor having an associated calibrated temperature function that is expressed as a function of a predetermined calculated parameter indicative of the actual differential temperature of a differential temperature source. The temperature source being calibrated is thermally imaged at different indicated differential temperatures to provide thermal images associated with the indicated temperatures, and such images are processed to define the calculated parameter as as function of indicated temperature. The calculated parameter function is substituted in the calibrated temperature function to provide a calibrated temperature function that is expressed as a function of indicated differential temperature.

Abstract: An apparatus for precisely controlling the movement and position of objects. The apparatus includes at least one moveable arm and a system for optically measuring the movement of the arm. The optical measurement system includes an optical fiber loop capable of producing microbend-induced optical attenuation when the loop is physically deformed by the movement of the arm. The apparatus further includes a signal source, a signal detector, and signal processing system for determining the attenuation of the signal between the signal source and the signal detector.

Abstract: An optical window that transmits infrared radiation and minimizes the effect of microwave radiation comprises:(a) a layer of a first material that transmits infrared radiation and absorbs microwave radiation, and has a predetermined thickness; and(b) a layer of a second material that transmits infrared radiation and has a low reflectivity for microwave radiation, having a thickness equal to one-quarter of the wavelength of the microwave radiation, and being located adjacent to the layer of the first material.

Abstract: A Raman converter comprising an input optical pump beam (16) from a laser (18) that propagates through first and second Raman cells (12,24) and causes Stokes shifted waves (14,26) to be generated therein, and a polarizer (34) disposed between the Raman cells (12,24). The polarizer (34) is switchable during laser operation to cause the Stokes shifted waves (14) from the first Raman cell (12) to be circularly or linearly polarized, thereby causing the Stokes shifted waves (26) in the second Raman cell to be generated as rotationally shifted or vibrationally shifted waves respectively. The polarizer (34) may be switched to the selected circular or linear polarization, or may be repeatedly switched therebetween at regular or pseudo-random intervals. A second polarizer (32) may be disposed upstream of the first Raman cell (12) for selectively switching the polarization of the input pump beam (16) during laser operation. The polarizers (32) and (34) may each be used alone or in combination with each other.

Abstract: A sensor and system for monitoring the accumulation of contaminants in oil wherein the contaminants have an electrical conductivity which is different from the oil. An electrochemical cell is used to measure the alternating current conductivity of the oil to provide an indication of the amount of contaminants present in the oil. Acids and water are two common engine oil contaminants which are accurately monitored by this alternating current conductivity measurement system.

Abstract: A Raman laser apparatus for producing a high energy output beam with low divergence. An optical pump beam (14) propagates through first and second focuses (34,36) inside a cell containing a gaseous Raman medium (20) at a pressure selected to promote stimulated Raman scattering (SRS) and suppress stimulated Brillouin scattering (SBS). The pump beam (14) generates a backward SRS wave at the second focus (36), which propagates back through the first focus (34) and acts as a seed for backward SRS therein. The backward SRS wave is amplified at the first focus (34), and extracted therefrom as an output beam (38) by output means (40). Any forward SRS wave which is generated at either the first focus (34) or the second focus (36) may be reflected back through the second focus (36) and then through the first focus (34) to further increase the backward SRS seed beam at the first focus. The output beam (38) is retro-reflected, and has beam divergence comparable to the pump beam divergence.

Abstract: A method for eutectically attaching a silicon chip to a gold-coated substrate. Prior to heating and scrubbing of the silicon chip against the gold surface, a gold lattice structure is placed between the silicon chip bottom surface and the gold surface. The gold lattice structure contacts the silicon chip bottom surface over an area equal to less than ten percent of the total surface area of the chip bottom surface. The point source contact between the gold lattice and silicon chip promotes formation of the gold/silicon eutectic alloy at temperatures of between 400.degree. to 475.degree. C. The gold/silicon eutectic alloy spreads between the silicon chip bottom surface and gold top surface to provide eutectic bonding. The method is especially useful in bonding relatively large silicon chips or dies to gold-coated substrates wherein the bottom surface or back side of the chip is not coated with a protective metal layer.

Abstract: An electrode apparatus for use in an electrochemical cell, which permits hydrogen gas generated at the cathode to be recirculated directly to the anode. The electrode apparatus comprises:(a) an ion-permeable membrane separating the anode and cathode compartments and liquids contained therein;(b) hydrogen electrodes (cathode and anode) in their respective compartments and in contact with the membrane, comprising a porous hydrophobic catalytic structure which permits the passage of hydrogen gas both along and perpendicular to the longitudinal surface of the electrode, and having an external portion extending outside of the elctrode compartment and exposing the edge surface of the electrode; and(c) a gas chamber connected to the external portions of the electrodes and providing for transfer of gas from the cathode directly to the anode.

Abstract: A filler composition having a coefficient of thermal expansion substantially equivalent to that of SiC foam and capable of fusing and integrally bonding to SiC foam. The filler composition is useful for bonding a surface layer to a SiC foam core for optical mirrors which are used in space applications and cryogenic detectors.

Abstract: Polymers of silanol-terminated aromatic imide compounds of Formula I ##STR1## where R.sub.3 and R.sub.4 are each selected from the group consisting of a C.sub.1 to C.sub.6 alkyl group, an unsubstituted aryl group and a substituted aryl group, Z is a divalent radical.A preferred copolymer in accordance with the present invention is formed by polymerizing the compound of Formula I with a silicon compound having the formula ##STR2## where R.sub.3 and R.sub.4 are as defined above, X=halogen, OH, OR, NRR, or ureido,Y=--O-- or ##STR3## p=1 to 10.

Abstract: The present optical system provides an all-reflective afocal reimaging system. A reflective system receives, by means of an entrance aperture, and reflects radiation or light through the system such that the radiation or light is imaged and recollimated as it is reflected through the system. The radiation or light exits at an exit aperture which is an image of the entrance aperture. High quality images of both the collimated scene and reimaged aperture are formed by the optical system. Embodiments are shown by which the optical system can be used as an optical derotation device by the inclusion of two planar mirrors located near the entrance and exit apertures.

Abstract: Silanol-terminated aromatic imide compounds of Formula I ##STR1## where R.sub.3 and R.sub.4 are each selected from the group consisting of a C.sub.1 to C.sub.6 alkyl group, an unsubstituted aryl group and a substituted aryl group, Z is a divalent radical.are prepared by:(a) reacting a bromoaniline compound with a chosen silylating agent to form a compound having the formula BrC.sub.6 H.sub.5 NSi(R.sub.1).sub.3 Si(R.sub.2).sub.3, where R.sub.1 and R.sub.2 are each a C.sub.1 to C.sub.4 alkyl group(b) reacting the compound formed in step "a" with n-butyllithium, followed by reaction with a chosen halogenated alkylsilane compound to form a compound having Formula II ##STR2## where R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are as defined above (c) reacting the compound of Formula II formed in step "b" with a dianhydride compound having the formula ##STR3## where Z is as defined above to form a compound having Formula III ##STR4## where R.sub.3, R.sub.

Abstract: A process for removing undesired material from a chosen substrate by exposing the substrate simultaneously to ultraviolet radiation and a selected dense fluid, wherein the radiation produces a photochemical reaction that removes the undesired material from the substrate and the dense fluid enhances the removal of the undesired material. In an alternative embodiment, a reactive agent may additionally be used. The process may be used to remove contaminants from a substrate, etch a substrate surface, or destroy toxic organic material in industrial wastes.

Abstract: A method and composition which provides both thermal control and electrostatic discharge protection to bodies in the space environment. The composition comprises: a) a chosen polymer or resin that forms a polymer that is an electronic insulator and is suitable for space applications; and b) a selected lithium salt as a dopant wherein said composition, when formed into a film or coating, provides a semiconductive film or coating having a volume resistivity of about 10.sup.6 to 10.sup.11 ohm-centimeter and a value of solar absorptance/total normal emittance within the range of about 0.305 to 0.595. In an alternative embodiment, the composition may optionally include tantalum pentoxide.

Abstract: A system and process for metering the delivery of liquids wherein the conductivity of the liquids is monitored at a metering device, such as a spray gun. Measurement of conductivity at the metering device provides continual measurement for fluctuations in conductivity and is useful for controlling liquid flow during sequential metering of different liquids.