This webpage contains information on the optical and mechanical characteristics of the main mirrors of WHT.
Main mirrors at WHT
The main optical system of the WHT consists of three mirrors, the primary, the secondary and the Nasmyth flat mirror. 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 |
Diameter of central shadow (mm) |
|
|
Primary |
Concave parabolic |
-1 |
4180 |
10439.6 |
|
Cervit |
1220 |
|
Secondary |
Convex hyperbolic |
-2.5329 |
1001 |
-3115.7 |
8035 |
Zerodur |
|
|
Nasmyth |
Flat |
0 |
616x432 |
|
1750 |
Cervit |
|
Mechanical specifications of the mirrors
|
Element |
Shape |
Total Diameter (mm) |
Expn. Coef. (1/K) |
Material |
Axial thickness (mm) |
|
Primary |
Concave parabolic |
4220 |
0.1±0.1x10-6 |
Cervit |
452 |
|
Secondary |
Convex hyperboloid |
1001 |
-0.7x10-6 |
Zerodur |
168 |
|
Nasmyth |
Flat |
616x432 |
0.1±0.1x10-6 |
Cervit |
51 |