Abstract: An automatic printed wiring (or circuit) board (PWB) method for detecting maximum line width violations is described. The method utilizes an array of optical sensors for optically inspecting a printed wire circuit. The array forms a binary image pattern of the PWB which is tested for compliance with logical rules of correctly printed PWB's regarding maximum line width. The detector comprises a plurality of CCD arrays arranged to form a series of pixels consisting of electronic binary signals corresponding to the instantaneous image viewed by each element in the CCD array. These pixels are formed in an image data stream of sequential pixels line-by-line of the CCD array, i.e., pixel sequential line sequential digital image data. The digital pixel data is formatted in an "N" by "N" bit matrix of points in proper image orientation. All such points are available for sampling. Each pixel progressively occupies each point in the matrix in proper orientation to its neighbors.

Abstract: A wavefront sensor for detecting the slope of an input wavefront. A surface acoustic wave reflective diffraction grating is positioned at a focal point of the wavefront, and generates surface acoustic waves at two primary frequencies f.sub.1 and f.sub.2. The reflective diffraction grating produces a first AC shearing interferogram between two like diffraction orders generated by the f.sub.1 and f.sub.2 surface acoustic waves. A photodetector array is positioned to detect the shearing interferogram at a two dimensional array of zones, and the phase of the output signal for each zone is representative of the local slope of the wavefront in the direction of shearing, thus producing the slope in one direction. Complete two dimensional wavefront slope information is obtained by shearing the wavefront in a second orthogonal direction in substantially the same manner utilizing a second surface acoustic wave diffraction grating and a second photodetector array.

Abstract: An optical encoder assembly includes an integral flexible coupler. A flange extending from the flexible coupler serves as a bearing retainer to hold a disc table and unitary bearing shaft in fixed axial position relative to the bearing. The bearing is further axially fixed relative to a stationary base which supports encoder disc illuminating and detecting optics. In a preferred form, the flexible coupler extends through the center of the encoder assembly, and a dust tube is positioned between the coupler and the encoder optics.

Abstract: An integrated wavefront compensator for an active optics system in which the components for detecting distortions in a wavefront and the components for correcting the detected wavefront distortions are integrated into one unit. The parallel processing channels of the compensator are fabricated simultaneously using simple, solid state components.

Abstract: A half tone screen of a graphic camera is uniformly exposed by a pinhole light projector positioned off axis with respect to the main optical projection axis. A light diffuser is positioned intermediate a light source and the pinhole has a variable density light attenuator pattern consisting of a plurality of circular lines for attenuating the light passing through the diffuser and aperture in a manner to produce uniform illumination of the half tone screen.

Abstract: A method of enhancing the production of typeset runarounds involves providing a set of light transmissive overlays having straight line rectangular grid configurations to the operator of the phototypesetter, together with a worksheet for recording line indentation data; selecting one overlay having horizontal grid line spacing corresponding to spacings between the lines of the text to be typeset, superimposing the selected overlay so that the edges thereof are aligned with the extremities of the text, recording indentation information which is readily made apparent by virtue of the overlay placement, and thereafter employing the recorded indentation data during the phototypesetter process.

Abstract: In an optically multiplexed angular encoder system, encoder illuminators are sequentially enabled and detected signals are sequentially stored. Such sampling and storage of the code track signals is repeated in successive sampling windows under the control of a free-running clock such that the information required to provide a multibit angular output is available for a near instantaneous output on command.

Abstract: Thermal actuator apparatus for controlling or adjusting the position of a surface or other object as a function of temperature. The principle of operation is the rate of change, as a function of temperature, in the modulus of rigidity or elasticity of counterbalanced springs of differing materials resulting in a change in equilibrium position. An actuating surface is coupled to the spring system, and its movement with temperature change can be used to change or otherwise control the position of an object.A simple adjustment is also provided to permit varying thermal coefficients of the actuator (magnitude of the response to temperature change).

Abstract: A measuring arrangement is disclosed for measuring the contour of a two or three dimensional surface in which a redundant configuration of distance measuring systems is positioned above the surface being measured. Each distance measuring system monitors distance measurements to a point proximate the surface as the measuring point is moved across the surface. The distance measurements are taken from a sufficient number of points on the surface such that a sufficient quantity of data is obtained to define the system geometry and also to define the position of each measurement point. The data is transformed by recognized mathematical techniques into the coordinate positions of all of the measured points on the surface.In one embodiment for measuring the contour of a three dimensional surface, a tetrahedral arrangement of four distance measuring interferometers includes three interferometers positioned in a planar array above the measured surface and a fourth interferometer positioned at a central apex thereof.

Abstract: An optical code disc includes a fine track which provides a high resolution signal, at least one V scan natural binary track synchronized to the fine track by lead and lag detectors, and Gray code tracks which provide the most significant bits of the digital output of the encoder system. The number of circuit elements in the multiplier circuitry associated with the fine track are reduced by means of a quadrant switching technique whereby the sinusoidal inputs to the multiplier are repeated through each quadrant of the fine track cycle. The V scan and Gray code tracks are optically multiplexed to reduce the number of leads from the optical detector. The use of both V scan and Gray code tracks minimizes the number of detectors required in the system while maintaining large detector signals from each track. The V scan and Gray code outputs are synchronized by the use of an overlapping bit.

Abstract: An optical code disc includes a fine track which provides a high resolution signal, at least one V scan natural binary track synchronized to the fine track by lead and lag detectors, and Gray code tracks which provide the most significant bits of the digital output of the encoder system. The number of circuit elements in the multiplier circuitry associated with the fine track are reduced by means of a quadrant switching technique whereby the sinusoidal inputs to the multiplier are repeated through each quadrant of the fine track cycle. The V scan and Gray code tracks are optically multiplexed to reduce the number of leads from the optical detector. The use of both V scan and Gray code tracks minimizes the number of detectors required in the system while maintaining large detector signals from each track. The V scan and Gray code outputs are synchronized by the use of an overlapping bit.

Abstract: A relatively simple wavefront sensor is constructed with an astigmatic optical system which focuses an indicent wavefront to x and y focal planes, with the x and y focal planes being relatively displaced along the optical axis because of the astigmatic nature of the optical system. An x modulation reticle is positioned at the x focal plane, and an x drive tuning fork drives the x modulation reticle in linear oscillation at a frequency f.sub.x to modulate the wavefront thereat. A y modulation reticle is positioned at the y focal plane, and a y drive tuning fork drives the y modulation reticle in oscillation, substantially perpendicular to the direction of oscillation of the x modulation reticle, at a frequency f.sub.y, different from the frequency f.sub.x, to also modulate the wavefront thereat. A detector array then receives the modulated wavefront, with each detector in the array receiving and detecting a different zone of the incident wavefront.

Abstract: An incremental slope wavefront sensor having an optical system which focuses an incident wavefront to a focal point. A novel modulation reticle is positioned at the focal point, and is driven in linear oscillation along a single axis. The modulation reticle has a modulation pattern formed thereon by alternating triangular light transmissive areas and inverted triangular light reflective areas. A first detector array detects the wavefront which has passed through the transmissive areas and diverged from the focal point in a two dimensional array of zones. A second detector array detects the wavefront which has been reflected by the reflective areas and diverged from the focal point in a two dimensional array of zones. The output signals from the first and second detector arrays for each corresponding zone are differentially combined to form a differential output signal for each zone.

Abstract: A beam director for an optical ranging system for measuring relative distance changes between first and second retroreflectors in which a beam of radiation is introduced between the first and second retroreflectors by a steering beam splitter pellicle positioned obliquely therebetween. A portion of the beam is reflected by the pellicle onto the first retroreflector, which reflects it back through the pellicle onto the second retroreflector, which in turn reflects it back onto the pellicle where it interferes with the radiation beam being initially introduced thereon. The pellicle is rotatable about two axes positioned substantially perpendicular to the radiation beam reflected between the first and second retroreflectors and steers the beam to compensate for relative movements of the retroreflectors. The arrangement is such that translation of the pellicle along any of three axes does affect the optical path difference between the retroreflectors.

Abstract: A highpass feedback loop for A.C. coupled amplifier circuits is disclosed, by means of which pulse undershoot recovery is accelerated. The feedback loop includes an operational amplifier which goes into limiting above a selected amplitude threshold so that for pulses exceeding the threshold the amplifier frequency response is unaffected.

Abstract: A cooled mirror structure useful in a high power laser optical system, constructed with a substrate formed of a material having a thermal conductivity peak in a cryogenic temperature operating range. During operation, the temperature of the substrate is maintained within the cryogenic temperature operating range to maintain the thermal conductivity within the peak, while the low cryogenic temperature also results in an extremely low coefficient of thermal expansion for the substrate. The combination of high thermal conductivity and a low coefficient of thermal expansion provides a mirror structure capable of handling extremely high energy flux loadings with a minimum amount of resultant surface deformation.

Abstract: A dual beam radar jamming system for detecting and separating each radar signal of a dual beam radar system and then generating selectively modulated dual return signals for transmission back to the radar source to deceive its tracking apparatus. The jamming system includes a control unit which enables an operator to simultaneously monitor and control the jamming of each beam of a TWS radar system.

Abstract: An arrangement for laser beam welding wherein at least one of the components being welded is formed of a material which is substantially transparent to radiation at the wavelength of the laser welding beam. A layer of welding material is placed over the surface area of the weld joint, and is a type of material which is substantially absorbent of radiation at the wavelength of the laser welding beam. The welding material is then irradiated by the laser beam through the component which is substantially transparent thereto for a sufficient period of time to cause melting of the welding material and fusion thereof to the two components being welded. The present invention has particular applicability to welding with a Nd-YAG laser of components formed of silica-containing material, such as fused silica or titanium silicate, and wherein the welding material placed at the weld surface area is a titanium based material.

Abstract: A technique for simulating various signals, such as from radar emitters, in a broad frequency spectrum by generating at any given instant only those of the signals that affect a receiver which is tuned to a particular bandwidth. As the receiver is tuned to a new bandwidth, the simulating system responds by quickly generating any signal or signals that exist in the new bandwidth.

Abstract: A bi-directional film transport device includes an upper and lower plate member having a separation gap between a first and second pair of drive rollers, the bytes of which are positioned adjacent the gap. A single drive motor is rigidly rotationally coupled to drive the first and second pair of drive rollers and the plate members function to eliminate the tendency of the film to buckle, which in turn maintains the film in the proper plane of focus. As a result of this simple arrangement, complex clutch mechanisms which are otherwise employed to maintain tension during bi-directional operation have been eliminated. Side walls coupled between the plates parallel to the path of film travel prevent skewing of the film driven by the short low inertia high speed drive rollers.