Abstract

An F/4 50-mm diam diffracting element has been designed and built to form a cylindrical line image of a CO₂ laser beam. The chirped grating with 5000 lines is arranged to be at an angle of 45° with the incoming beam; this allows a FOV of ~20° to yield very high diffraction efficiencies—>90%. The grating is made with a conventional wet-etch process in the photoresist and an overcoating of gold is used to maintain the very high efficiency. The polarization of the incoming em wave must be controlled relative to the grating orientation. There are variations in the image quality as a function of the grating approximating and manufacturing technique. Measurements were made in the focal plane using pyroelectric detector with a 12-µm aperture mounted on a scanning x-y table. Results are displayed with an oblique histogram presentation.

© 1989 Optical Society of America