Optical testing of a gamma-ray telescope mirror
Abstract
A large size concave mirror for use in the gamma-ray telescope TACTIC was tested. Focal length of the concave spherical mirror of diameter 600 mm was measured to be 401.2 cm using the Ronchi test. The surface accuracy of the mirror was estimated to be about Lambda/2 by visual observation of the fringes obtained. The spot size of the mirror for a nearly collimated beam was measured to be about 0.5 mm, whereas the computed size of the spot for a spherical mirror is about 0.1 mm. The reflectivity of the mirror was measured to be about 83% in the visible region.
- Publication:
-
Bulletin of the Astronomical Society of India
- Pub Date:
- September 1993
- Bibcode:
- 1993BASI...21..527U
- Keywords:
-
- Gamma Ray Telescopes;
- Mirrors;
- Performance Tests;
- Reflectance;
- Ronchi Test;
- Surface Finishing;
- Aluminum Coatings;
- Collimators;
- Curvature;
- Focusing;
- Astronomy