
Using the OPD fan
The OPD fan is a plot of the optical path difference versus pupil coordinate.
To create a OPD fan window:
- Select from the menu Analysis > Fans > OPD

The OPD is displayed as a function of the normalized pupil coordinate. Both a tangential (y) and a sagittal (x) scan is made, with the sagittal scan plotted as a dashed curve (for an on-axis field point these scans coincide). The curves can correspond to different field points at a constant wavelength, or to a particular field point with different wavelengths. The options button will summon a utility window that will let you change the number of points at which the OSC is calculated, the field(s) of interest, and the wave(s) of interest.