Hi Gabriele,

Geometric Bitmap Image Analysis is very similar to Image Simulation in that BMP or JPG source bitmaps can be imaged through an optical system. But generally speaking, Image Simulation will give much higher signal-to-noise ratio images more quickly than Geometric Bitmap Image Analysis, although this latter provides a useful double-check on the predicted performance.  

With GBIA, the signal/noise is proportional to SQRT(n), where n is the number of rays traced per pixel. Detecting under sampling in the PSF grid of Image Simulation is trickier. Badly sampled PSF grids almost always look like delta functions, which means that the convolution-based method may predict performance that is better than is achievable in reality if the PSF grid is not set up adequately. And I think this may be the reason why you don’t see the obscuration in your analysis.

I’d recommend to follow the steps explained in this article How to simulate high resolution images – Knowledgebase (zemax.com) to adjust the Image Simulation settings, but feel free to share your system with us if you still have a large discrepancy between the two analysis.

Best,

Dear Berta,

thanks for the reply and the article and excuse for the delay of my answer. If I understand well you say that between the two image analysis methods I should prefere the Image Simulation tool to the GBIA. Unfortunately I cannot share my design for copyright issues.

I thank you nevertheless for your suggestion.

Best regards