Design optical surface as the measurement datum in measuring gear tooth flank by symmetrical laser interferometer

Abstract

Laser interferometry is a promising method to measure the form deviation of gear tooth flanks. The lack of measurement datum is the bottleneck problem of measuring a gear tooth flank by laser interferometry. Manufacturing a physical reference gear tooth flank as the measurement datum has many drawbacks which restrain the application prospect of measuring gear by laser interferometry. Optical surfaces are more mature to manufacture and have much higher processing accuracy compared with the physical reference tooth flank. Thus, we design and use an optical surface as the measurement datum. First, we invent a symmetrical oblique incidence laser interferometer (SOILI) to reduce the interference fringe’s density and enhance the tractability of interferograms. Second, we propose a design method for calculating the measured tooth flank’s similar optical surface. Lastly, we propose the nonparallel plate model which is a general form of the parallel plate model and can be used to calculate the situations where the normal directions of the measured surface and the reference surface are different. Experimental results verify that an optical surface can be designed and used as the measurement datum. Furthermore, this research provides some references for the measurement datum in the relevant comparative measurements processes by laser interferometry.