Contrast factor of the F-P etalon and blocking filter assembly

1) Center Wave Length (CWL) and bandpass (FWHM) as a function of f-ratio of the telescope and tilt of the F-P filter (in collimated beam, telecentric beam or non-optimized telecentric system)

2) CWL shift and FWHM broadening in non telecentric systems (refractors and Cassegrain telescopes) and useful formulae

3) Daystar filter modelling and additional results

4) Air-spaced F-P etalon theoritical performances and comparison with mica-spaced etalons

5) Analysis of the PST modification (air-spaced F-P etalon) and comparison between collimated and telecentric mounts

6) Contrast factor of the F-P etalon and blocking filter assembly

7) Contrast factor of the F-P etalon : test of various stacking schemes

8) Fabry-Perot math and bibliography

Experience with various stacking schemes for etalons in rear position

Test 1 : Daystar PE 0.6A versus Daystar PE 0.6 A + Omega 4.5 A

Test 2 : PE 0.6A, PE 0.6A + TO 0.9A, Ion 0.3A , PE 0.6A + Ion 0.3A

Test 3 : PE 0.6A, PE 0.6A + 0.9A etalon, Ion 0.3A

Test 3 : Daystar PE 0.6A versus Daystar PE 0.6A stacked with 0.9A etalon

(Takahashi TOA 150)

The 0.9A etalon has a good transmission :

The exposure time with the PE 0.6 A + 0.9A etalon is 3.3 x the exposure time with the PE 0.6A. By comparison, the exposure time with the Ion 0.3A is 6.7 x the exposure time with the PE 0.6A.

Daystar PE 0.6A (left) compared to Daystar PE 0.6A + 0.9A etalon (right) :

The benefit of the 0.9A etalon is obvious. The granulation (from the photosphere) is much less visible with the 0.6A + 0.9A stack.

Daystar Ion 0.3A (left) compared to Daystar PE 0.6A + 0.9A etalon (right) :

The CWL is probably not the same in both images.

Return to home page