Patent ID: 7724409

Claim:
A system for recording and reproducing a holographic interferogram on a holographic storage medium with an optical servo, comprising: a light source generating a signal beam and a reference beam, the reference beam being projected to the holographic storage medium in a first incidence direction, and the signal beam being projected to the holographic storage medium in a second incidence direction; a spatial light modulator and an image sensor on the path of the signal beam, such that the signal beam passes through the spatial light modulator to reach the holographic storage medium, and interferes with the reference beam to generate the holographic interferogram in the holographic storage medium, and when the reference beam is projected to the holographic interferogram in the first incidence direction again, a reproducing beam is generated and is projected to the image sensor; a reflecting mirror reflecting the reference beam passing through the holographic storage medium; a reference beam sensing portion receiving the reflected reference beam and converting the reflected reference beam into a first electrical signal; a servo beam guiding portion guiding the reference beam to pass through the holographic storage medium, and guiding the reflected reference beam the reference beam sensing portion; a servo light source generating a servo beam, the servo beam being projected to a servo track of the holographic storage medium through the servo beam guiding portion, and being reflected by the servo track; a servo sensing portion receiving the reflected servo beam and converting the reflected servo beam to a second electrical signal; and a controlling device analyzing the first and second electrical signals, so as to adjust a distance and an incident angle between the reflecting mirror and the reference beam to ensure that the reference beam is projected to the holographic storage medium in the first incidence direction, and to ensure that the holographic interferogram is continuously recorded in the holographic storage medium along the servo track.