Zero Working Distance Objective?

[LukeMelo]

Hi all, I'm new to the forum so I hope this is the right place to post this kind of question.

I've built an interferometric scattering microscope (inverted) which measures the interference between backscattered light from a coverslip and particle respectively.

Currently the setup uses objective oil and a coverslip, however I'd like to remove these from the equation and drop a sample directly on the objective itself.

My question: does a High NA objective with zero working distance exist?

I hope this figure helps clarify what I'm talking about.

Thanks,
- Luke

[microb]

Isn't this traditionally done with an overhead water dipping objective?

https://www.thorlabs.com/newgrouppage9. ... n=N20X-PFH

[LukeMelo]

Isn't this traditionally done with an overhead water dipping objective?

https://www.thorlabs.com/newgrouppage9. ... n=N20X-PFH

Interesting, thanks for the link. I see these all have a working distance varying from 0.5-3mm. I'm looking for something with zero working distance (even though this seems odd to focus at the exit of the objective).

[apochronaut]

The solution would therefore be your immersion medium. What is the n of your solution?

[ChrisR]

If you move "tube" lens too close to the objective, the latter will focus closer, probably as close as the front surface, as a retrofocus optic does.
The effect would be more noticeable if you used a finite objective with the same tube lens. Try one with the TL setup you have now?
The effect on IQ won't be pretty but it may help with your investigations.

[Brad_]

LOMO has made some "contact" objectives. There's five of them on eBay as I write.

I have no idea of how they are used or even what they are used for.

Have fun.

Brad