I've developed a Windows program called Foucault Unmasked that analyzes unmasked Foucault Test images. This method results in more objective and accurate mirror profiles than can be obtained by eye using a Couder mask or Everest pins. The number of zones is limited only by memory space.
The program automatically crops the images to the edges of the mirror and finds the precise radius of null zones (to sub-pixel accuracy). Note that automatic cropping requires a dark background. Pre-cropped images can be used, but the Crop checkbox must be unchecked in that case.
Results can be saved in the format used by Figure XP or by Sixtests so that those programs can be used for subsequent analysis the zone data. A native CSV format is also provided that can be loaded into Excel.
For convenience, the program includes a native surface analysis (with surface plot) based on ATM Mirror Mathematics by Jim Burrows (click the Show Results... button). This has not been extensively tested so it is best to compare the results with those produced by Figure XP or Sixtests.
In testing the program, I had access to images from a limited number of mirrors. I used my own 6" F8 images and images of a 450mm F3.56 mirror kindly provided by the Mark Cowan. My own results on Mark's images nearly match those he obtained using a manual flip-diff image processing method to find null zones.
In testing I also generated 40 Diffract images of a simulated perfect parabolic mirror. These images were analyzed yielding an RMS of 2 nm and Strehl ratio of 0.998. The difference from perfect is largely due to the simulated diffraction effects near the edge.
The Help button in upper left hand corner of the main window provides an Overview of the software and instructions for use. You will need Microsoft .NET version 4 or later.
I have placed the windows installer file "Setup.msi" on the file sharing site "ge.tt". To download the file click on this link http://ge.tt/6wDoeNn2. A large grey window will appear (after the ads) containing "Download Setup.msi". Click on "Download" and then run the downloaded Setup.msi file (just double click on the file) to install Foucault Unmasked. (The file size is about 1 MB).
The program is added to the startup menu as "Foucault Unmasked".
Let me know about your experience or if you have any problems, questions or suggestions.
Here are some screenshots showing the analysis of Mark Cowan's images: