Laser profilometer for on-line measurement of the micro-p rofile of superfine surfaces

A Laser profilometer with sub-nanometer level reso luti on to measure the superfine surfaces is described in the paper. Its based on the principle of differential interferometer,the measurement and reference ar ms of this profilometer are designed as coaxial,moreover, an optional divided structure wit h birefringence crystal that can avoid the noise caused by reflected light is ap plied to the instrument, so the system has excellent vibration resistance and low noise. Under the circumstance when vibration amplitudes reaches 300nm, the measuring noise is kept less than 1nm. The on-line version of t he profilometer can be put on the kniferest of a diamond lathe to measure the mi c ro-profile of ultra-precision machining surfaces. The vertical resolution and t he lateral resolution are better than 0.2 nm and 0.5μm, respectively.