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Abstract

A method and apparatus 10 for sensing and measuring the quality of the wavefront of a substantially collimated incoming optical beam 12. Incoming beam 12 is directed through a polarizer 14 and toward a polarizing beam splitter 14 where it is separated into an S-polarized beam 18 and a P-polarized beam 20. Beams 18,20 are directed in opposite directions along a common closed path of a modified cyclic interferometer 22. This closed path includes mirrors 24,26 and focusing means 28,30 for focusing the P-and S-polarized beams 18,20 at a common focal region on the path and for recollimating each beam 18,20 after it passes through the focal region. At the focal region is located a specially constructed polarizer component 32 with an optical aperture 34. The aperture 34 is centered on the centroid of the focused beams and is angularly oriented about an optical axis of the closed path so that it transmits substantially all of the beam traveling in one direction and is an effective optical spatial filter for the beam traveling in the opposite direction. After being recollimated and returned to beam splitter 16 the beams 18,20 are recombined in a common path 36 and oriented in a common plane of polarization by polarizer 38 thereby causing them to interfere. The resultant fringe field is read by reader 40 and analyzed by receiver electronics 42, control electronic means 44 and memory device means 46. The apparatus 10 can operate with either a continuous wave or a pulsed wave of incident optical radiation.

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First Claim