Interpolate ray trace PSF for the field height and angle.
PSF = rtPSFInterp(optics,fieldHeight,fieldAngle,wavelength)
fieldHeight (m) represents the distance from the center of the image.
xGrid, yGrid (m) sampling grid in meters
fieldAngle (deg) is the angle.
wavelength: Wavelength field of the optics data (nm)
When we store the PSF, it has unit area. The returned value also has unit area.
Thus, no light is lost by application of the PSF.
See rtApplyPSF for an example call.
Copyright ImagEval Consultants, LLC, 2003.