resolution of lens

soldevilla · Post by **soldevilla** » Thu Mar 09, 2017 5:39 am

I'm thinking to adjust the magnification that I get, I want to say that the diffraction point of the lens matches the pixel size. In this way I can work perhaps with objectives with more work distance to get the same enlargement without losing quality.

I need to know the pixel size of my camera (easy, it is published) and the resolution power of my lens. I know that there are engraved glass discs to test the resolution, but they are expensive. Does anyone know of an alternative system to check the resolving power of each objective?

thanks

Beatsy · Post by **Beatsy** » Thu Mar 09, 2017 6:37 am

A rough guide is 0.55/(2NA) - that will give you the resolution in microns. Multiply by the magnification for the size "on sensor"

ChrisR · Post by **ChrisR** » Thu Mar 09, 2017 8:53 am

It won't go as far as theory might appear to predict. You need a few pixels to see what's going on, sensors usually have some filtering, and the contrast near the diffraction limit is low.

Above (say) 5x it'll be hard to get objectives even near the pixels reolution.

EG using 0.55/2NA

If you take a Mitutoyo 50x/NA 0.55
Resolution = 0.5µ
or 25µ on screen
with a 4µ pixel, it's rather more than 6 pixels to see very much.

You cannot use a short enough Tube lens to reduce magnification enough to get near "pixel sharpness"!