Active spectrographs: a new way to improve their quality

摘要

We discuss the various errors affecting an astronomical spectrograph, whether mounted directly at the telescope, or placed on a table. We then propose a method for measuring these errors, using the Shack-Hartmann principle, which has been successfully used in the field of active and adaptive optics. It is argued that such a measurement can be used to correct the aberrations on-line, leading to considerable improvement in the performance of the spectrographs, as well as leading to much reduced costs.