Design and Fabrication of a Holographic Diffractive Optical Element

Abstract

This thesis presents the design and fabrication of a holographic diffractive optical element (DOE) similar in concept to a Dammann grating that produces an array of uniformly spaced laser beams of equal irradiance. To produce an angular offset between the 0th order and the array of higher order beams, two-dimensional computer-generated hologram (CGH) design techniques are employed. Starting with a base Gerchberg-Saxton algorithm, modifications are introduced to factor in the source distribution and to make the array of beams more uniform in irradiance. An initial design, fabrication, and test phase is carried out using a 650 nm source to allow for rapid on-site design iteration cycles and the timely correction of unforeseen issues before samples are fabricated for a 1064 nm source. Fused silica etch process development is done in parallel with the design iterations. Preliminary samples are fabricated using pre-established grayscale photolithography procedures, and the final sample is etched into fused silica to be used in an undisclosed high-power application.