3D surface topography measurement of diffractive optical element based on white light interferometry stitching method

Abstract

Diffractive optical element (DOE) has been widely used in camera lens imaging systems such as mobile phone camera, Monitoring Camera, etc. The measurement of the DOE surface morphology is very important to evaluate the processing quality of the elements, optimize the manufacturing technology and improve the image quality of the imaging system. However, traditional DOE has a small diameter (about 10mm) and the base surface is a wavelength scale 3D relief microstructure. It is a great challenge to realize the high-precision, high-efficiency and multi-scale surface profile measurement of its full aperture. In this paper, new white light interferometry scanning stitching measurement device and method for the 3D surface topography measurement is proposed. Firstly, the white light interferometry scanning stitching measurement device was established. Then, a total of 67 subapertures of the full aperture of the element were measured based on the experimental device. Finally, the profile error of the full aperture was obtained by a microstructural subaperture stitching algorithm. The RMS normal error of the surface profile is 0.3717μm. The measurement results verify the effectiveness of the scanning stitching measurement system and method based on white light interferometer.