Overcoming practical limitations of Even Order Missing gratings and Diffractive Optical Elements to improve diffraction pattern fidelity and contrast in machine vision applications.

摘要

We show how inevitable Diffractive Optical Elements (DOEs) fabrication imperfections lead to parasitic orders in the diffraction patterns of Even Order Missing (EOM) gratings and DOEs, limiting the attainable pattern signal to noise ratio (SNR) in machine vision applications. Using odd pixel numbered target patterns is then shown to be a highly effective simple way of eliminating the problem.