Fan Out Diffractive Beam Splitter; 5 Phase Level Binary versus 50 Phase Level Grayscale

摘要

A high efficiency diffractive optic is created by the combination of high-quality design and a suitable fabrication process that can actually realize the design. Between design and fabrication is the tooling, in this case a photo mask. It is this tooling that is critical. Choosing, Binary or Grayscale methods to fabricate the structures that represent the design can be a daunting task. In many cases, grayscale design doesn't always provide the best solution or cost benefit during product development. This paper will compare and contrast the design and performance of a 1 to 24 beam, two dimensional; beam splitter fabricated using a fifty (50) phase level grayscale and a five (5) phase level binary fabrication methods. Optical modeling data will be presented showing both designs and the performance expected prior to fabrication. An overview of the optical testing methods used will be discussed including the specific test equipment and metrology techniques used to verify actual optical performance and fabricated dimensional stability of each optical element. Presentation of the two versions of the splitter will include data on fabrication dimensional errors, split beam-to-beam uniformity, split beam-to-beam spatial size uniformity and splitter efficiency as compared to the original intended design performance and models. This is a continuation of work from 2005, Laser Beam Shaping VI, where a 2 level binary design was compared to the grayscale design.