Sensitivity of a telecentric assembly to tilt
(Copyright Christian Viladrich)
Telecentric systems for solar observation
Tilted telecentric systems
Focuser "droop" case: What happens when a telecentric system is tilted ?
Suppose the telecentric assembly and the
etalon are aligned along the same optical axis, but with a tilt i
relative to the telescope optical axis.
In the following OSLO simulation (Newton 300 mm f/5.5 with 5x
telecentric) the telecentric system is tilted by 2° relative
to the telescope optical axis (solid line pink color).
Light comes from the left side.
The chief rays angle is no more normal to the etalon, but tilted by an angle on the order of i/M. This angle is relatively constant over the field covered by the camera.
Here are the results of the simulations of two configuration using ray-tracing software.
The tilt of the chief ray results in a blueshift of the CWL and a
broadening of the FWHM of the etalon which can be calculated with the
formulae given on this page:
../FP.htm
Noteworthy, in both simulation the degradation of image quality
(spherical aberration, astigmatism, etc.) due to the telecentric tilt
is very limited.
f/5.5 Newtonian telescope with 5x telecentric, no tilt:
f/5.5 Newtonian telescope with 5x telecentric tilted by 2° on optical axis:
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