Non Uniform illumination or vignetting in miniscope?

[kyrollosyanny]

Hi all, I tried to test my miniscope imaging a green slide to see how even the illumination is and if there is any vignetting in the system. I observe the image to be a lot darker at the edges (image attached), I wonder if this is due to nonuniform illumination or vignetting and what should I do to fix it?
Thank you

[Daniel Aharoni]

Hi kyrollosyanny,
Proper positioning of the excitation LED and half-ball lens will decrease vignetting but it is true that you can't get rid of it completely. During offline analysis you can normalize the pixel intensity across all columns which does a decent job of making the image uniform but with the downside of increasing noise around the edge of your image.

[kyrollosyanny]

Thank you for the reply