1. Bath Interferometer for ATM's
Presented by:
Dale Eason
Yahoo group Interferometry

2. Attributes of a good telescope mirror
Proper correction
Figure of merits are RMS and Strehl ratio
Good edge. Not turned and a smooth surface overall
No good numerical test for this. Difficult to measure quantitatively. Foucault and Ronchi images can give a good qualitative test.

3. Bench Testing Telescope Mirrors 4.25 F10
Foucault
Ronchi

4. Interferometry

8. 18 X 2 inch Pyrex mirror
Hand placed on upper right edge for one minute.
Average of 5 interforgrams taken over 5 minutes

10. Interference of waves of same frequency.
Waves in phase that sum
Waves 90 degrees out of phase

25. Many line interferogram

40. Test stand induced astig of 16 x 1 inch mirror

41. Astig Zernike terms turned off

42. Air currents in the test path

43. Many line interferogram

44. FT analysis of Interferograms
Advantages
Hi resolution detail
Higher accuracy
Better resolution of the mirror edge
No fringe tracing
Disadvantages
Adds more noise to the analysis
Requires more Images to remove the noise

52. Limitations Micro surface smoothness
Ronchi and Foucault images are better but are only qualitative tests.
Edge condition
Ronchi and Foucault images are better methods

53. Bath Interferometer for ATM's
Presented by:
Dale Eason
Yahoo group Interferometry