Question regarding 'crosstalk' when changing from a collimated to lensed radial detector array

[JAMCO]

I do x-ray cameras, never visible light optics but here I am, trying to change a collimated detector array into a lensed array. I am such an idiot about this stuff I barely know where to look to find the answer I am questing after, so I came here. I bet someone knows the answer off-hand. Basically, I have about 50 detectors organized radially like spokes on a bicycle wheel, all looking at the center. Each detector peers through a set of converging lenses, like small telescopes. There are always at least two wavelengths of light isotropically radiating from the isocenter (excitation and fluorescence)and I need to block one and pass the other, so an array of movable filters for each channel, corresponding to the different wavelengths of interest, up to several. The detectors are crazy sensitive...photon counting but not energy discriminating so leakage & 'cross talk' is a big problem.

In the collimated detector, we took great pains to shield light leakage channel-to-channel with exquisite baffling and anti-reflecting and anti-emitting coatings, and also between filter elements for each channel. Here comes my question: will a lensed detector like I describe be as sensitive to photons scattering into the objective lens from outside the field of view? For example, could I use a contiguous, cylindrical filter to block the excitation frequency for the entire radial array instead of individual filters and all that baffling? The guy who knew about all of this left the company six months ago and is not available to consult with, so I hope that this forum can help me converge on at least a concept for a solution. Thanks for any advice.

 

[IRstuff]

If you mean lenslets that are basically in close proximity to the detector front surface, then, actually, even more so. The baffling in the collimator would have blocked out of FOV photons, but lensed detectors count on other optics to limit the FOV of the detector. The goal of the lenslet is to ensure that photons entering the physical footprint of the detector actually get detected by virtue of the fact that the lenslet takes light impinging on the detector footprint and focuses the light into a spot in the center of the detector. The detector would be physically configured to take advantage of that. However, that means that the FOV of the detector is actually quite large, and it assumes that there are additional optics that would limit the field angle of the lenslet to what's permitted by the other optics.

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