Wide-spectrum laser beam shaping for full-color volume holographic optical element recording

For homogeneous diffraction efficiency of the recorded volume holographic optical element (vHOE), a recording beam of uniform intensity is required. A multicolor vHOE is recorded by an RGB laser source with Gaussian intensity distribution; during equal exposure time, recording beams of different intensities would result in different diffraction efficiencies in different recording areas. In this paper, we present a wide-spectrum laser beam shaping system design method, by which the incident RGB laser beam can be controlled into uniform intensity distribution with a spherical wavefront. This beam shaping system can be added to any recording system to obtain uniform intensity distribution without altering the beam shaping effect of the original recording system. The proposed beam shaping system is composed of two aspherical lens groups, and the design method with an initial point design and optimization design method is given. An example is built to demonstrate the feasibility of the proposed beam shaping system.