A digital holography microscopy system for DOE measurement

Abstract

A Diffractive Optical Element (DOE) is passive optical component containing complex micro structure patterns which can transform light in predetermined way. It can realize almost all the same optical functions as conventional refractive optics such as lenses, prisms or aspheric lenses. The microstructured surface relief profile has three dimensional features with widths and depth tolerance on the order of micrometers or less. Thus any minor error in design or fabrication will result in huge deviation from the desired optical function and performance. Therefore measurements of DOE before and after fabrication are important. The objective of this system is to measure DOE prior to and after fabrication for both design verification and fabrication quality validation. Digital Holography Microscopy (DHM) method is the methodology to be implemented. The measurement of the DOE design before the real sample being fabricated is realized by using a liquid crystal spatial light modulator (LCSLM) loaded with designed DOE pattern simulating the DOE sample. Featured with low cost, non-invasive, real-time, high-resolution and full-field measurement for entire effective area of DOE, the system is versatile in measuring different types of DOE.