Abstract: An extended scene wavefront sensing apparatus and procedure that separates (deconvolves) scene effects from wavefront errors of an optical or similar system. The present wavefront sensing apparatus and procedure uses a point source wavefront slope sensor in scene scanning mode and estimates wavefront errors by using a cross-correlation or cross-coherence procedure that operates on the outputs of the point source wavefront slope sensor. A signal processing procedure employed by the point source wavefront slope sensor provides output signals corresponding to wavefront slopes at forward optics pupil locations geometrically projected to the location of the transmission and reflection measurement plane detector pairs. During the scanning process, each of the detector pairs (equivalent to a subaperture) measures the effects of the local unchanging wavefront error in the forward optical system and temporal variations due to the scanning scene.

Abstract: Relative piston misalignments between segments of a multisegment optical system, such as a segmented primary mirror, are reduced by a method in which elements of an arbitrary unknown extended scene image carried by an input beam are eliminated from the beam's error information in performing an error calculation. After appropriately processing the beam with the specialized sensor elements, spatial frequency domain representations of a variety of optical images are obtained which correspond to both individual segments, and to multiple combinations of segments of the optical system; each combination is preferably composed of two individual segments. The spatial frequency domain representations of the individual segments are then subtracted from the representations of the segment combinations to obtain spatial frequency domain functions for the combinations.

Abstract: A shearing phase difference sensor including a high energy laser source for generating adjacent coherent light beam. Samples of the beams are extracted by an extracter and directed to an optical modifier. The optical modifier, positioned for intercepting the sample beams from the extracter, diffracts the beams and produces output beams which, in turn, are directed through a lens to a detector. The detector, positioned to intercept the output beams, produces electrical signals indicative of the output beams. The electrical signals are processed by a processor which calculates the phase difference between adjacent coherent light beams. Also, disclosed is a method for measuring the phase difference between adjacent coherent light beams.

Abstract: An adaptive laser system (10) incorporates a laser (12) and a novel system and method for determining the slope distribution of a laser beam wavefront. The sensor comprises a ramp filter (16) with a continuous monotonically varying transmittance function and two intensity distribution sensors (18 and 20). Lenses (24, 26 and 28) are provided for focusing and collimating the laser beam as appropriate. A processor (22) calculates the slope distribution from the two intensity distributions obtained by the intensity sensors. The slope calculations can be used to determine commands to predistort the laser beam to approximate a desired flat wavefront at the sensor. The transmittance function of the ramp filter is linear and its spatial width is considerably larger than the expected spreading of the beam due to distortions in the wavefront.

Abstract: A complex optical system may be maintained in alignment by means of a technique in which an analytical model of the system is utilized which is assumed to be capable of essentially optimal performance. A physical example of the same system design is then assembled and a plurality of performance characteristics are measured related to the intensity function associated with a point source image on the system's focal plane detector array. A plurality of specific adjustments are then calculated by means of a second order approximation technique which would have the effect of degrading the performance of the analytical model to equal that measured for the physical example, whereupon compensating physical adjustments are made to the physical example to improve its measured performance.