Design and implementation of an atmospheric dispersion compensator/corrector for the Gemini Multi-Object Spectrograph

The Gemini Multi-Object Spectrograph (GMOS) was delivered and commissioned at the Gemini North Observatory and it has been in regular science use since November 2001. While GMOS-North met all its reliability and performance requirements on flexure, image quality and throughput, the high velocity precision (2 km/sec) mode will not be implemented until the Atmospheric Dispersion Compensator/Corrector (ADC) is delivered and commissioned. The ADC optical design incorporating two bonded prism pairs and two corrector lenses is described along with its opto-mechanical and software control design considerations as related to the overall system requirements including: image quality, error budget, optical mounting, opto-mechanical packaging, mechanism control, handling, deployment and telescope observational control considerations.