Temperature Compensation Servo Algorithm for Holographic Data Storage

Photopolymers are widely used as media for holographic data storage because of their high dynamic range, high photosensitivity and availability. However, the most photopolymers have a large coefficient of linear thermal expansion. Therefore, it is known that the temperature changes cause deterioration of readout image under the Bragg-mismatch conditions. This paper proposes a new servo algorithm which includes both the servo error signals detection method and the automatic compensation procedures with feedback servo for the holographic data storage system. Experimental results for the proposed technique are demonstrated for temperature changes of up to +25 K successfully.