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New long trace profiler for aspheric optical surface metrology

A long trace profiler (LTP) is specially designed for the metrology of long aspheric optical surfaces and has been widely used in the fields of synchrotron radiation and astronomy. An LTP with an innovative design has been successfully developed at SSRF. An f-θ system based on phase plate diffraction collimation is employed for the first time. Effect of source instability and ambient factors on the precision is greatly reduced, compared to other LTPs now available. The scanning range is 350mm, precision better than 0.5μrad, static repeatability 0.1μrad. The profiler has been calibrated by a standard mirror from Chinese National Institute of Metrology.