Screenshots Project Pane Measurement Pane Image Pane Analysis Pane

This image shows the project pane, where you can specify the parameters of your mirror and describe the project. At bottom left is the list of all the measurements you make as the polishing and figuring progresses.

This pane shows the details of a single measurement. You can specify the date when you made the measurement and describe what was done to the mirror prior to it. This information is indispensable when learning the effect of various figuring strokes. At bottom left is the list of all images that comprise this measurement, along with knife offsets at which they were taken and details of where exactly in the image the mirror appears.

This pane is for setting image parameters. The buttons along the top are used to align the circular outline with the mirror in the image, and to specify the orientation of knife edge. At right is an entry for knife offset (in millimeters) and a checkbox for excluding the image from the analysis.

• Numeric results include common measures of mirror quality: Strehl ratio, RMS and P-V deviation from parabola. They are calculated for the entire mirror and the visible portion separately.
• Surface deviation graph shows the deviation of the surface from the nearest parabola in nanometers. This graph tells which regions need to be polished away.
• Zone ROC graph is the input into calculating the surface deviation. This is what is measured in the traditional Foucault test with a Couder mask, i.e. the distance between knife and mirror where a zone darkens equally on opposite sides.
• Asymmetry graph shows the relative difference in illumination of the two halves of the mirror as a function of knife offset. This graph shows the results for a single zone, which is selected by double-clicking on the Zone ROC graph.
• Axis alignment graph shows any systematic drift in asymmetry, which indicates that the knife is not moving exactly along the axis of the mirror. Misalignment results in systematic error on the measurement of surface shape.
• Image contrast helps adjust camera exposure and filter for the best possible dynamic range. Knife alignment should be tweaked to push the downward "kink" (around 30mm in the image) as low as possible; measurements for zones inside of the kink are increasingly unreliable.

Maintained by Dejan Vucinic <dvucinic (at) users.sourceforge.net>
Last updated on May 26th, 2002.

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