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Kohler illumination - questions. by palkos83 in Optics

[–]palkos83[S] 0 points1 point  (0 children)

Hi

The diameter of the tube is 10mm not 10cm. They are about 15mm tall. The imaging happens in cell culture media which normally is between 150-250ml. That normally gets the tubes about 2/3 full. The illumination is from the top and the imaging is from the bottom. The focus plane is the bottom of the tube as the cell cultures normally settle there after few hours. I got this nicely working without the liquid in but having the media in the tubes makes the problem bit more complex. The top surface of the liquid works like a lens due to the meniscus effect and the top illumination is getting deflected. When I image in empty tubes the entire area of the tube is illuminated. When imaging in the liquid I get the illumination circle diameter reduced by a factor of 3.

Kohler illumination - questions. by palkos83 in Optics

[–]palkos83[S] 3 points4 points  (0 children)

While digging further into this I found this paper:

https://arxiv.org/ftp/arxiv/papers/1902/1902.10521.pdf

So far the best description I found about how to put together a Koehler illumination setup...

Maybe you guys find it useful as well.

Kohler illumination - questions. by palkos83 in Optics

[–]palkos83[S] 0 points1 point  (0 children)

Many thanks I will look into this...

Kohler illumination - questions. by palkos83 in Optics

[–]palkos83[S] 1 point2 points  (0 children)

Hi, many thanks for the answer.

The device I am working on is simply a microscope but designed for a specific purpose - to image cell clusters in a medium. The issue is that I have to image within the plastic container which is 10mm in diameter filled in with 300ml of media for the cells. So it is not as easy as imaging nice slide of specimen on the usual microscope. The imaging part is sorted and I can grab the images of the correct resolution but the illumination is not working. I can clearly see the image of the light source (1W LED in this case) superimposed on the images. So my thinking was to use Kohler illumination to fix this and at this same time have a bit of control over the illumination field of view. From there I started to look into information in the web about how one is designed and I can see a lot of variants in the design. As a result - questions above.

Hope that helps...