Filter Measurements for ACAM / Seminar Series (1)

Speaker: Annemieke Janssen, PhD Student
Affiliation:Rijks Universiteit Groningen & ING student
Title: Filter Measurements for ACAM
Date: 10 December 2010
Place: ING+NOT Astro-seminar- Santa Cruz-La Palma- Spain

Abstract:

During the last three months the Transmitted Wavefront Distortions (TWD)
of almost all 50-mm filters have been measured. These distortions are
important to know since they affect the image quality of ACAM
observations. For other instruments the TWD is less critical since filters
are usually placed in the focal plane, where they only affect the image
quality locally. ACAM is a bit of an exception having the filters placed
near the pupil plane, where wavefront distortions over the whole filter
area affect the image quality.

We started analysing the results, partly with Zemax and partly with
pinhole experiments. In the last case, calibration lamps and a pinhole in
ACAM create a very tiny spot on the CCD. The effect of a filter placed in
the beam can now be compared with the measured TWD. The first results will
be discussed in an half-hour presentation.