DESI corrector lens

DESI's corrector is designed to provide a larger field of view to the focal plate, allowing 5,000 fibers to be arranged over 8 square degrees.

The design includes four large lenses composed of fused silica. The two smaller lenses are aspheric on one surface; all other silica surfaces are spherical. An atmospheric dispersion compensator (ADC) is included in the design, in order to meet blur requirements at off-zenith angles. This compensator includes two large wedged borosilicate lenses with spherical surfaces.