Holographic optical elements (HOE) for semiconductor lasers

A two step method is described to produce off-axis holographic lenses with high diffraction efficiency and without astigmatism for semiconductor lasers. The hologram is recorded in the visible (514 nm) and reconstructed in the infrared (800 nm). The principal parameters (recording and reconstruction angles, astigmatic focal lengths) for each hologram and wavelength are calculated analytically using second order approximation. Numerical methods, based on classical ray-tracing applied to holographic diffraction, have been developed to calculate spot diagrams and to investigate the effects of higher order aberrations.