An alternative mirror design for use in planar laser-scanning displays

Abstract

This paper describes the mathematical results of an investigation into the design of a rotating mirror for use in a laser-scanning display. The main design parameter considered in this work was the scan linearity. Using geometrical optics, the requirements of linearity result in a system equation of the quadratic differntial type. The mirror's shape was determined from the system equation in two ways. First, by approximate analytical solutions and, secondly, by numerical integration using a Runge-Kutta method. The linearity predicted by the Runge-Kutta method was essentially perfect, which supports the validity of the system equation. The linearities predicted by the approximate analytical solutions were satisfactory over a wide range of screen distances and display sizes. It is concluded that the application of this system equation will allow greater flexibility in the design of planar laser-scanning display systems when rotating mirrors are employed. Experimental results reported here support this view.