SYSTEM AND METHOD FOR LIMITING THE EFFECTIVE COHERENCE LENGTH OF A SOLID-STATE LASER IN HOLOGRAPHIC RECORDING

摘要

The effective coherence length of a single-frequency, solid-state laser is limited to reduce spurious, secondary holograms in conjunction with a holographic recording. The wavelength of the laser is varied or 'scanned' with high precision over a very small wavelength range. In an embodiment, the temperature of the laser's resonant cavity optical bench is altered, causing the dimension of the cavity to change and the emission wavelength to move in a controlled manner. The changing wavelength is monitored at high resolution, and a feedback control loop updates the temperature set-point to keep the monitored laser wavelength moving at a desired rate of change through a desired range. As the wavelength of the laser is scanned, the phase of the holographic interference pattern is locked at a position of maximum coherence/contrast within the holographic film aperture.