Two-mirror device for laser scanning systems: Multi-parametric analysis

Most laser scanners applications require a linear scanning function, i.e., a constant scanning speed. One of the possible and simplest methods to achieve this - for both scanners with rotational (i.e., polygonal) or oscillatory (i.e., galvanometer) mirrors - is to increase the distance between the mirror and the scanned plane. In order to achieve this, we propose and study a simple and low-cost optical configuration with two plane mirrors set at a certain adjustable angle. The multiple reflections of a laser beam on the two mirrors are considered, the number of images produced is deduced, and the total optical path is obtained. The device is considered for a dimensional measurement application, usually called an optical micrometer - in a set-up which includes the two angular mirrors between a laser scanner with oscillatory or rotational mirrors and its objective lens. This simple device increases the path of the laser beam between the scanning mirror and the lens in a compact construct. The linearity of the scanning function is thus increased, while the total size of the system is reduced - with regard to other possible set-ups. A multi-parameter analysis is proposed and briefly pointed out with regard to the characteristics of the system.