OUTPUT STABILIZATION FOR A LAZER MATRIX

摘要

A projection device comprises a matrix (1) of semiconductor lasers, an optical system (2) for projecting the matrix (1) on an element (3) illuminated by the projection device, and a control device (9) for controlling the semiconductor lasers through a feedback device. The feedback device comprises a first detector (13, 14) for detecting the intensity of a light spot from a semiconductor laser on the illuminated element (3). The first detector (13, 14) generates a first signal representing the detected intensity. In a first adjusting phase, the semiconductor lasers are controlled and the intensity of the light spot is adjusted to a desired value by means of the feedback device. Simultaneously, light originating from a semiconductor laser controlled during the first adjusting phase is detected by a second detector (18), and a value of the detected signal is stored in an addressable memory cell. In this way, the first adjusting phase comprises filling of memory cells for each controllable semiconductor laser. In a second adjusting phase, occurring during the use of the projection device as such, the amount of emitted light is stabilized every time for each semiconductor laser by detection through the second detector (18) and comparison with the value stored in the memory (29) for the relevant controlled semiconductor laser.