Previous: Focal modifying lenses
Up: Design
Next: Hartmann unit
Previous Page: Focal modifying lenses
Next Page: Hartmann unit
There is a choice of two collimators, one coated
for the short wavelength region (Å ) and one for
longer wavelengths (
Å ). They are off-axis paraboloids,
with a measured focal length for
both collimators of 2359
0.5 mm and an off-axis
distance of 295
0.5 mm, implying an off-axis angle of 7.18
degrees. Space constraints mean that the instrument has in fact been
constructed assuming an off-axis angle of 7.39 degrees. The diameter
of the collimated beam is 215 mm in the absence of focal modifiers.