The program uses an iterative technique to improve the accuracy of measurement of higher order aberrations in the presence of strong low order aberrations. The spatial resolution obtainable on the wavefront is limited only by the resolution and SNR of the extra-focal images. The accuracy obtainable is dependent on the details of your optical system, the sampling and SNR of the recorded images, but is usually of the order of a few 10's of nm RMS. Measured errors may vary, depending on the characteristics of your optical system and the quality of your extra-focal images. Currently the program is restricted to optical systems that have circularly symmetric pupils.
The program is based on the Tcl scripting language with the Tk and BLT GUI extensions. We have added several new commands to the basic Tcl/Tk functionality to implement this program. The GUI driven version of the program should be used for most routine data analysis. A batch mode program is also supplied, which enables simple scripts to be written to reduce large amounts of data, or to enable the program to be used as part of an automatic active optics system. The functionality of both the GUI and batch programs may be extended by writing additional Tcl code and/or incorporating third party Tcl extensions. The program is supplied dynamically linked1 to enable easy inclusion of third party extension, and to promote conservation of system resources.