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Newtonian Primary Test Data
View Your OMI Mirror Test Data
It's part of our mission to provide you, our customer, with clear test data to demonstrate the quality of your mirror. We realize that the optics in your telescope represent a substantial part of the overall investment you've made in astronomy. There should be no doubt about the quality of your primary mirror. To prove our commitment to quality assurance we post test images and interferometric data for every OMI mirror we make.
We've organized the test data according to mirror size, with a page for each.
Click on the size of your mirror to access your mirror's test data:
12.5" | 15" | 18" | 20" | 25" | 30" | Custom
Test data produced BEFORE July 3, 2007 is presented as a web page (HTML).
Test data produced AFTER July 3, 2007 is in downloadable PDF format. |
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Below is a sample of the Interferometric Test Data and corresponding images you'll find for each mirror, and some tips on how to interpret the test data.
Interferometric Test Results
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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 18" F/4.5
Serial# 18-105-071604
- Strehl ratio: .940
- RMS wavefront error: .038 λ
- Focal length: 81.8"
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| Null Ronchigram |
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Null Laser Interferogram |
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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 |
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Contour Plot |
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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.
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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.
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We've organized the test data according to mirror size, with a page for each.
Click on the size of your mirror to access your mirror test data:
12.5" | 15" | 18" | 20" | 25" | 30" | Custom
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If you have questions about your test results contact me, James Mulherin via E-mail: jcmulherin@opticalmechanics.com or telephone (319) 351-3960
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