Method for making a holographic mirror

DETAILED DESCRIPTION Accordingly, an object of the invention is to develop a simplified and improved process for making extended holographic mirrors.
According to the invention, this object is achieved by illuminating a photosensitive layer in lines or strips using at least one laser beam.
At the same time, the photosensitive layer and the laser beam are continuously moved relative to one another in a crosswise direction at a speed that guarantees sufficient illumination of said layer.
According to the improved process, one method uses a divergent, static laser beam to form on the photosensitive layer, a light strip extending in a first direction.
A second method uses a laser beam that forms a small light spot on the photosensitive layer that is dynamically deflected by a light deflection system in a direction different from that of the relative movement of the laser and the photosensitive layer.
In the process according to the invention, the creation of the standing wave in the photosensitive layer is not performed in a purely static manner by extended exposure of the entire surface but rather, in a continuous manner by illumination of a portion of the entire surface and by continuous relative movement between the laser beam and the photosensitive layer.
The relative speed of the photosensitive layer and the beam, as well as the intensity and the width or diameter of the laser beam must then be matched so that the necessary light energy is applied to the photosensitive layer.
Due to the continuous relative movement between the laser beam and the photosensitive layer, it is possible to make holograms of practically unlimited length in this manner.
The speed of the relative movement between the laser beam and the photosensitive layer in its longitudinal direction is limited by the intensity of the laser that produces the light beam.
To further increase the speed of the relative movement, the photosensitive layer can be exposed to beams from several lasers simultaneously.
In this case, however, care must be taken that the interference structures produced by the various lasers do not mutually obliterate themselves