This webpage contains information on the optical and mechanical characteristics of the main mirrors of INT.
Main mirrors at INT
The main optical system of the INT consists of two mirrors, the primary and the secondary mirrors. The summary of the characteristics could be found in the following table.
Summary of the mirror characteristics
|
Shape |
Asphericity |
Working Diameter (mm) |
Focal length (mm) |
Separation from primary (mm) |
Material | |
|
Primary |
Concave parabolic |
-1 |
2540 |
7475 |
|
Zerodur |
|
Secondary |
Convex hyperbolic |
-2.214 |
531 |
-1813 |
6017 |
Fused silica |
|
Finder: Primary Flat |
Parabolic Flat |
-1 0 |
405 135 |
2104 |
1600 |
Pyrex Low expn glass |
Mechanical specifications of the mirrors
|
Element |
Shape |
Total Diameter (mm) |
Expn. Coef. (1/K) |
Material |
|
Primary |
Concave parabolic |
2540 |
-0.7x10-6 |
Zerodur |
|
Secondary |
Convex hyperboloid |
531 |
|
Fused silica |
|
Finder: Primary Flat |
Parabolic Flat |
405 135 |
Pyrex Low expn glass |