Design and characterization of DOE micro lens array for spatial light modulator

In the Multi-point Diffraction Strain Sensor (MDSS), a micro lens array is installed in front of the camera as the key component for wavefront sampling. Alternatively, a liquid crystal spatial light modulator (LC-SLM) can be used to replace the physical lens array, on which we have designed various Diffractive Optical Element (DOE)- based micro lens arrays to display. However it is difficult to investigate the quality of these lenses by traditional metrology since the wavefront profile is modulated by the inner LC cells instead of the solid surface of optical components. In this paper, we introduced the Digital Hologram (DH) method to characterize the quality of these DOE-based micro lenses or lens arrays by measuring the whole phase profile of outcome beam through the SLM. First the design formula of the DOE micro-lens array is given. Then the characterization procedure for such lens array is demonstrated. The reconstructed results of the lens profiles are shown, which can be used for further qualification.