Micro Lens Mismatch & Energy Loss

  • 7 March 2022
  • 1 reply

Hello all,
I have a sensor with micro lens array on top, the use of the micro lens is to achieve higher efficiency for higher values of angle of incident. 
I optimized my design and have different values of chief ray angle from that of the micro lens array, I would like to know how much energy I am losing due to this mismatch?
Unfortunately I don't have the micro lens design or any parameters to simulate the lens, the only things I know is the pixel size (3micron) and a table that tells me the CRA for each location on the sensor.
Any help would by appreciated.


Best answer by Angel Morales 25 March 2022, 20:05

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Hi Bentzi,

Thanks for posting in our forums!

I wanted to clarify some details -- is your design a system that is imaging onto this sensor+microlens combination? Do you have angles of incidence from this design onto the microlens+sensor combination? I am a bit unsure of the information you have in-hand.

I ask this because I think it might be tough to extract energy loss due to the CRA mismatch without knowing what your microlens will do to the chief ray of your field points after they exit your optimized design. It seems like it’d be a bit of guesswork without knowing something like focal length of the microlens to have some really rough approximation. Is there any kind of information about how that “CRA for each location on the sensor” is generated? As in, does it tell you what the incident CRA is on the microlens first also? I think you’d need some more information to start to get at the results you’re looking for.

If you do happen to get some information on a mapping of “chief ray angle on the microlens → chief ray angle on the sensor” across different sensor points, you could perhaps approximate the efficiency with something like a coating on the image surface. We have a TABLE coating definition where you can specify reflectivity/transmissivity at different wavelengths and angles of incidence. You can look at the Help File page “The Libraries Tab > Coatings Group > Defining Coatings > The TABLE Data Section ” for more information. You might only want to be looking at chief ray transmission data for this approximation, though, as other rays in the pupil will certainly have different angles of incidence on your microlens array.

Let us know if you have any more questions, and thanks again for your post!