A VERY WIDE FIELD, VERY FAST TELESCOPE

摘要

A 1.3 meter aperture Cassegrain telescope with a very wide flat field has been completed and is now producing images. The field of view is a stunning 1.7 degrees while the focal ratio is a very fast F/4. The telescope is located at the United States Naval Observatory Flagstaff Station in Arizona, USA. The authors discussed the concept of a fast, very wide flat field optical system years ago, but no system was built. Now the system has been realized using only primary and secondary mirrors with a small fourth order (Schmidt plate) corrector. The mirrors form a modified Ritchey Cretien' system but are significantly more aspheric-especially the secondary mirror. The corrector was made using the vacuum technique invented by Bernard Schmidt. The resulting optical system is unique. The design performance, optical fabrication techniques, and optical test results are discussed. Images taken with the system are also displayed.