Method for Calculating the Scanning Unit of a Laser Scanner and Optimizing Its Overall Dimensions

Abstract

A prism deflector, which is a multifaceted prism with reflective edges, is the most common scanning element that allows fast filling of a wide scanning area with laser radiation pulses along one coordinate. To carry out the movement of laser radiation along the second coordinate of the region under study a second scanning element, for example, a flat oscillating mirror, should be used. The overall dimensions of the scanning elements and the scanning unit as a whole depend on the free parameters that are set at the system development stage. The paper proposes a mathematical model designed for automated calculation of a scanning unit consisting of a prism deflector, a fixed flat mirror, an oscillating flat mirror, and a laser exit window. The described model makes it possible to calculate the overall parameters of system optical elements and the layout of the block based on the required characteristics of the scanned area and free parameters, which include the angle of radiation supply to the face of the prism deflector, the tilt angle of the fixed mirror, and one of the coordinates of the laser output window position relatively to the center of the prism deflector. In this case, the first two mentioned parameters are of the greatest interest from the point of view of minimizing and optimizing the overall dimensions of the scanning elements and the scanning unit as a whole. Based on the above model, an analysis of the dependence of the overall dimensions of the scanning elements and the scanning unit as a whole was carried out. The paper describes the layout features of the scanning unit. Recommendations for choosing the value of such free parameters as the angle of radiation supply to the face of the prism deflector and the angle of inclination of a flat fixed mirror are given. The obtained results can be used in the development of automated systems for the design of laser scanning devices.