A Manual Method for Interpretation of Nominally Plane Wavefronts Available to Purchase

Interferometry is a testing tool widely used within the optics industry; however, consensus standards have not been available for the analysis of test results. Subcommittee F01.02 on Lasers of Committee F-1 on Electronics of the American Society for Testing and Materials has adopted as a tentative standard the ASTM Interpretation of Nominally Plane Wavefronts (F 529-77 T), which determines the maximum peak-to-valley wavefront deviation for the test specimen. Quantitative information is extracted from an interferogram by comparing an actual fringe pattern to an ideal pattern of equally spaced straight lines. The comparison is made by superimposing a set of straight lines on the fringes of the interferogram and measuring the deviation of the interferogram fringes from the straight lines. An interlaboratory round-robin test using three interferograms of varying sizes and wavefront errors was conducted to evaluate this method. The precision was found to be dependent on the particular interferogram. For two interferograms it was 1/20 λ at 633 nm and for one interferogram, 1/10 λ. The method has the potential for wide use and can minimize disputes between parties.