Simplified Multi-wavelength Laser Speckle Contrast Imaging System by Using Single Holographic Optical Element

Abstract

A simplified multi-wavelength laser speckle contrast imaging system by using a single holographic optical element is proposed. By using the optical properties of holographic optical element (HOE), which has transparency and angular selectivity, the HOE can replace many optical elements. The HOE functions as an integrated optical element: multi-wavelength beam guiding optics. To record the HOE, recording wavelength precompensation method is used for providing flexibility for recording setup. By adopting the precompensation method, volume gratings to be utilized by various wavelengths can be recorded by a single wavelength laser system. For using multiple wavelength with a single HOE, wavelength-multiplexing is conducted by controlling exposure durations on medium. To verify the feasibility of proposed method, the diffraction efficiency of HOE is measured.