Abstract: Coherent light from a laser is directed through first and second two dimensional planar arrays of lenslets which are moved relative to each other to enable the beam to point along any diffraction order, and fine pointing of the beam between orders is accomplished by slightly changing the angle of incidence of the beam with respect to the arrays. The laser is replaced by a photoreceptor when the scanner operates as a light beam receiver.

Abstract: A system for determining the position of an object in which a moving periodic pattern is projected onto the object. A sensor on the object generates a sensor signal related to the periodic pattern. A reference signal is generated relating to the position of the moving periodic pattern. The sensor signal and the reference signal are compared to determine the position of the object. The pattern may be generated by projecting light through two gratings which are separated and have the same pattern. Errors created by instability or nonisotropy can be corrected employing a third grating having a different pattern and generating a correction value related to the difference between the position of the object determined employing the pattern generated by the two gratings and the pattern generated by the third grating. The moving nature of the pattern may be created by employing a fixed projector and a moving mirror.

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 target is illuminated through an optically distorting region, such as atmospheric turbulence or non-precision optics, by coherent light and a first set of data is recorded indicative of the complex amplitude of scattered radiation and such target is thereafter illuminated by incoherent light to produce a second set of data indicative of the nature of the region; the second set is divided into the first set, and the resulting data is Fourier-transformed to produce a diffraction-limited target image.

Abstract: A microscope, not employing conventional optical elements, is disclosed wherein a sample under examination is subjected to a moving pattern of illumination having alternate light and dark interference fringes, and having a spatial frequency which varies during the motion of the fringes over the sample in a first direction, in order to obtain the sine components of the optical image of the sample. The light reflected off of the sample is gathered by a wide angle light detector to produce electrical signals which in turn result in the recording of a set of signals proportional to the intensity of the light reflected from the sample during a plurality of signal sampling intervals. Another set of signals is recorded after the direction of relative motion between the pattern and the sample is changed by about 1.degree., for example, and so on until electrical data is recorded for a considerable number of "fourier slices" across the sample object.

Abstract: A test target for adaptive optics comprising, in the preferred embodiment, a plurality of nine adjacent, stacked, and aligned rows of a multiplicity of alternate opaque sections and transparent sections in a repeating bar pattern, with all sections being positioned on a flat transparent medium (such as film or glass), and with each opaque section being an opaque bar and with each transparent section being a transparent bar. Each row has a different spatial frequency than any other of the nine rows, with the spatial frequency of any one row being of a different multiple of the row having the lowest spatial frequency. As a matter of preference, the nine adjacent, stacked, and aligned rows are stacked with the first and lowermost row having the lowest spatial frequency, and with the ninth and uppermost row having the highest spatial frequency.

Abstract: A sensitive wavefront sensor combining attributes of both a Hartmann type of wavefront sensor and an AC shearing interferometer type of wavefront sensor. An incident wavefront, the slope of which is to be detected, is focussed to first and second focal points at which first and second diffraction gratings are positioned to shear and modulate the wavefront, which then diverges therefrom. The diffraction patterns of the first and second gratings are positioned substantially orthogonal to each other to shear the wavefront in two directions to produce two dimensional wavefront slope data for the AC shearing interferometer portion of the wavefront sensor. First and second dividing optical systems are positioned in the two diverging wavefronts to divide the sheared wavefront into an array of subapertures and also to focus the wavefront in each subaperture to a focal point.

Abstract: A beamformer device for forming at least one beam from the outputs of a sensor array, including: a plurality of radiation sources; means for providing to each radiation source a signal from an associated one of the sensors in the sensor array; a detector array of radiation-sensitive means for providing a series of spaced signals representing radiation incident from each of the radiation sources; and means for varying the delays between the spaced signals for optimizing the response of the device to a signal from a predetermined direction.

Abstract: A range imaging system in which a periodic pattern is projected onto the scene to be imaged. Three frames of intensity values are collected as the pattern shifts 120.degree.. The phase by which variations in range cause portions of the pattern to shift are determined from the three frames of data as being proportional to range. To generate the phase information, the intensity value for each pixel in the third frame is subtracted from intensity values of the same pixel of the first and second frames. The arc tangent of a function of these difference values represents the phase shift, and thus range.

Abstract: A range imaging system in which a moving periodic pattern is projected onto the scene to be imaged. The phase by which variations in range cause portions of the pattern to shift are monitored to develop range data. A television camera offset from the axis of illumination generates four frames of intensity values. The moving pattern shifts one-quarter cycle with respect to the pattern between each of the frames. The data from the third frame is subtracted from the first frame and the data from the fourth frame is subtracted from the data of the second frame to cancel the effects of background illumination. The first difference represents a sine signal and the second difference represents a cosine signal. The arc tangent of the quotient of these values represents the phase, and thus the relative range of various points in the image. The moving pattern can be generated by either a translating plate or rotating disk which has a periodic variation in transmissiveness.

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.