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In order to promote the measurement accuracy to sub-50 nrad rms for both spherical and plane mirror tests and to resolve the difficulty in testing strongly curved mirror by use of the NOM, the Nano-accuracy Surface profiler (NSP) was developed. The NSP system applies scanning sampling beam in fixed scanning distance combined with non-tilted reference beam for removing pitch error of scanning slide to ensure sub-50 nrad rms accuracy measurement. The NSP takes the advantage of the NOM in using precise autocollimators (ELCOMAT 3000) for both sampling and reference beams. The NSP verifies at least same measurement accuracy as the NOM for plane mirror test. The NSP system scheme, scanning sampling beam in fixed distance, significantly reduces test error than the NOM for sphere test, and it also ensures the capability using single calibration curve to further correct systematic error in reaching sub-50 nrad rms accuracy for spherical mirror test.
Who am I?
Qian, Shinan, from graduation to 1991, he worked at Tsinghua University, Anhui Institute of Optics and Fine Mechanics, and the University of Science and Technology of China in the fields of optics, optical instruments, interferometers, metrology, and x-ray lithography. From 1992 to 1996, he was with Sincrotrone Trieste, Italy, where he directed the Optical Metrology Laboratory. Since 1997, he has been with Brookhaven National Laboratory for developing nano-accuracy surface profilers. |
