Study on the new manufacturing and testing technologies of Free-form surface optics

Free-form surface optic is one of the most advanced technologies in the field of optical engineering. Free–form surfaces have smaller off-axis aberration over traditional symmetrical lenses, but are much more difficult to fabricate and evaluate. The ultra-precision machining technique is elaborated from the perspective of optical elements’ processing and testing methodology. In addition, several promising testing methods, computer generated hologram and reflection grating photo-grammetry, introduced. Finally, strengths and weaknesses of the two methods are summarized.