From my understanding, the method used to compute the relative illumination is based on sequential mode
From the doc :
This feature computes the relative illumination (RI) as a function of radial y field coordinate. RI is defined as the intensity of illumination per unit area of image surface normalized to the illumination at the point in the field that has maximum illumination (which may not be on axis). The computation considers apodization, vignetting, apertures, aberrations of both the image and pupil, variations in F/#, chromatic aberrations, image surface shape, angle of incidence, and optionally, polarization effects assuming unpolarized light. The method is based upon one described in M. Rimmer, "Relative illumination calculations", Proc. SPIE Vol. 655, p99 (1986). The published method was extended to include apodization, transmission, polarization, and non-planar image surface effects. The computation method assumes the following are all true:
- The object scene is plane, uniform, and Lambertian.
- The image surface is a reasonably good conjugate (that is, an image) of the object surface, so that rays coming from small patches of light on the object surface are imaged to patches of light on the image surface. Aberrations are fine, but the rays should be reasonably localized on the image surface.
- The exit pupil is not too close to the image surface. This condition will be satisfied if the F/# is larger than about 0.1 and the ray aberrations are small compared to the exit pupil distance.
- The cosine space aberrations are not so severe as to form caustics in angle space. A caustic in angle space means that rays in different parts of the entrance pupil have the same angle in image space. To check this, use the "Direction Cosines" option on the spot diagram feature (See the “Standard Spot Diagram” analysis).
The relative illumination is computed by integration of the effective area of the exit pupil as seen from the image point(s). The integration is carried out in direction cosine space using a uniform grid in image cosine space.
Note that the RI computation will not in general yield a cosine-fourth curve, because the so-called cosine-fourth "law" is actually an approximation based upon a thin, slow, aberration free lens with the stop at the lens. For more general lenses, including telecentric, aberrated, or vignetted lenses, the RI can be computed using an integration of the projected solid angle or effective area of the exit pupil as seen from the image location, and this computation will not yield a simple cosine-fourth curve. If a system violates the assumptions of the computation an error message will be displayed and the RI will not be computed.
My question is can the relative illumnation results be obtained using non-sequential mode ?