Does encircled/ensquared energy analysis account for system throughput?

Question

I’m calculating infrared power densities in w/cm² of near-diffraction limited star images from a system that has variable vignetting over the field of view. Does the diffraction EE analysis ignore or account for system vignetting and light loss due to obstructions? What would the right way be in Zemax to calculate radiometric irradiance from point source images that are affected by vignetting and that vary slightly in structure from DL over the focal plane?

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Best answer by Sandrine Auriol 6 July 2022, 11:19

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Sandrine Auriol · Accepted Answer

Hi MikeThe diffraction EE takes into account system vignetting due to obstructions, meaning that those obscured rays will not be part of the encircled energy calculation. However we still consider that the EE reaches 1 on the image plane, so the 1 doesn’t reflect the energy loss throughout your system.I checked this on this system"{Zemax}\Samples\Sequential\Telescopes\Schmidt-Cassegrain spider obscuration.zmx".

Mike.Jones · Answer

The PSF intensity should be radiometrically accurate, showing the true irradiance in w/cm² at the image plane. This is what sensor pixels respond to. A check box could be added to FFT and Huygens PSF routines to account for system throughput, including attenuations due to surface reflections and bulk absorption. This would give true focal plane irradiance. Can you set up a poll to query users about this?

Does encircled/ensquared energy analysis account for system throughput?

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