Question
Why don't the image analysis routines work with my system?
Synopsis
Problems with image analysis routines.
Solution
By far the biggest problem encountered in this area is the failure to use adequate pupil sampling to characterize the image. To compute a spot diagram, point spread function, or MTF, OSLO traces a grid of rays from the current object point to determine the wavefront in image space. For systems in which diffractive effects are important, there should be several grid cells per wavelength OPD, to prevent inadvertent order skipping. For analyses produced using FFT (e.g. point spread function) the pupil sampling is determined using the number of rays across the pupil, one of the parameters of the analysis command. For analyses produced using general ray tracing (e.g. spot diagrams or interferograms), the pupil sampling is determined using what is called the aperture division factor, also one of the parameters of the analysis command. The aperture division factor is also a spot diagram condition and can be set independently of a particular analysis command.
