
Using the Fourier PSF plot
The Fourier PSF plot displays an image of the point-spread function (PSF) as calculated using the discrete Fourier transform (DFT).
To create the PSF plot window:
- Select from the menu Analysis > PSF > Fourier
Exporting data from PSF plot
The underlying data I(x,y) may be exported using the Export toolbar icon, or by "Save data as..." on the contextual menu (obtained by control clicking on the image).
Options panel
- Field
- Using the Field popup menu, select the field for which you wish to calculate. Select All to calculate for all fields (this can be very time-consuming).
- Wave
- Using the Wave popup menu, select the wave for which you wish to calculate. At present only the monochromatic diffraction OTF may be calculated.
- Pupil sampling, number of rays per side
- The pupil is sampled using a rectangular N by N grid of points that contains the pupil (if vignetting factors are zero). N is the "number of rays per side".
- Interpolation order
- To produce a smoother PSF or LSF, you can use this control to increase the order of Fourier interpolation used. The pupil data is Fourier transformed to produce the PSF, and this data is then (Fourier) interpolated to increase the resolution. The interpolation order is the number of doublings of the resolution.
- Draw Airy disk
- If checked, the Airy disk is drawn. n.b., this enables image resampling.
- Draw rays
- If checked, the geometrical rays are superimposed on the PSF image. n.b., this enables image resampling.
- Resample image
- Resamples image to center the pattern and make the image a specified minimum resolution, in case you wish to copy it out or save it.
- False-color image
- Colors instead of intensity shading.
- Enhance faint features
- Uses a nonlinear intensity map to amplify weak features.
- Negative image
- Reverse shading for high and low intensity.