Fabrication of apodized apertures for laser beam attenuation

To obtain maximum energy output from a high-power laser system it is necessary to carefully shape the input beam's cross-sectional intensity profile. This avoids diffraction-produced hot spots which can cause damage to the amplifier components. The intensity should be at a maximum in the central part of the beam and fall of gradually at the edges to avoid hard-edge diffraction effects. This kind of beam profile can be produced using an apodized aperture — a soft-edged aperture that may be constructed in various ways. This report describes a photographic rotating-film technique for fabricating apodized apertures from photo-sensitive glass plates.