Reading device

Abstract

A reading device includes a spatial light modulator, a zoom lens set, an object lens, an image sensor, and an adjusting module. The spatial light modulator provides a reading beam. The zoom lens set forms the reading beam into a real image. The object lens focuses the real image onto a collinear holographic storage medium and thus produces a diffraction signal. The image sensor converts the diffraction signal into an electric signal. The adjusting module adjusts the optical magnification of the zoom lens set according to the quality of the diffraction signal.