Telescope Mirrors: Newtonian Primary Test Data OMI Mirror # 20-128-010107 Interferometric Test Results These results are measured on the wavefront using a 533 nm laser. The results are then scaled to 550 nm, which is the center of the visible spectrum or the wavelength that your eye is most sensitive to. OMI 20" F/5 Serial# 20-128-010107 Strehl ratio: .940 RMS wavefront error: .039 λ Focal length: 99.8" Null Ronchigram Null Laser Interferogram These images are taken just inside the focus of the parabolic mirror. The mirror is auto-collimated against a precision optical flat to produce a null test. Because these images are created using a null test, a perfect mirror would exhibit straight Ronchi and interference fringes. The deviation from straightness in the images indicates the residual error on the mirror's wavefront. Click the following links to learn more about making a qualitative interpretation of the mirror's wavefront quality using the Null Ronchigram and the Null Laser Interferogram. Synthetic Fringes Contour Plot We provide the Synthetic Fringes graphic to allow an apples to apples comparison of different mirrors. There tends to be some variability in the visibility of the Null Laser Interferogram images from one computer/browser to the next. The Synthetic Fringes solve this problem. The Contour Plot shows you the shape of the mirror's wavefront relative to a perfect wavefront. The contour lines in the Plot can be interpreted just as you would interpret lines of equal elevation on a contour map. The contours run from high-red lines to low-blue lines. The number at the top of the Plot indicates the elevation change in waves between the contour lines. In this case there are .030 waves per contour. If you have questions about your test results contact me, James Mulherin via email: jcmulherin@opticalmechanics.com or telephone (319) 351-3960

This page last modified: Saturday, August 4, 2007 @ 10:50 PM CST