Experiments with the laser-ablation-made modified uniformly redundant array coded aperture performed in the visible spectral range

Abstract

We describe the process of preparing an experimental study of a coded aperture in the visible spectral range. In the experiments, shadowgrams are supposed to be recorded with a conventional imaging sensor. A feature of the work is a proposed coded aperture implementation method based on surface evaporation by laser ablation. As a coded aperture base material, a glass substrate with a titanium film 500-nm thick deposited on it is used. To characterize and validate the fabricated coded apertures, a dual-metric method based on image processing techniques was developed. The method was used to optimize laser parameters, including the pulse power, the spot moving speed, and the pulse repetition rate. The coded aperture implemented with the parameter values determined was then used as the imaging device in the experimental stand and proved to form a high-contrast image. The double metric method allows one to optimize other laser parameters, along with the studied ones, for the given experimental conditions.