"OEM Nikon 20x 0.75 VC" cover slip thickness

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Lou Jost
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Post by Lou Jost »

Chris those are good finds! If accuracy is not important for that application, that could be a good thing. With variation comes the chance that we could find just the right thickness eventually...

Munich
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Post by Munich »

Lou Jost wrote:Munich, I recognize those figures from the patent application referenced in our original thread...I imagine the text is just a Japanese translation of the English in that application?

https://patents.google.com/patent/US8143599
you are right. my bad.

Pau
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Post by Pau »

In the patent document fig. 14 there is "an infinite space compensator 122"

Does anyone know what kind of optics is it?
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Lou Jost
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Post by Lou Jost »

Pau, as I understood it, that was for an implementation which included the option to focus on either the upper or lower inner surface of the flow cell. Abednego shows that the actual implementation only focuses on the lower inner surface, so no compensator would be needed because the objective would be optimized to image that surface.

I know this doesn't answer your actual question, but earlier it was suggested that this compensator would be a weak negative lens element.

Pau
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Post by Pau »

Lou Jost wrote:I know this doesn't answer your actual question, but earlier it was suggested that this compensator would be a weak negative lens element.
Yes, I recall it, although it seemed just a guess. It it were a weak negative lens it would not project the image to infinite but "past infinite". If so, it could be done focusing the tube lens itself past infinite, just placing it nearer of the the sensor

I tried to discuss it at
http://www.photomacrography.net/forum/v ... 901#222901
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Lou Jost
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Post by Lou Jost »

Your idea of how to correct for cover-glass mismatch using the tube lens focus is very interesting! Time to experiment.

ChrisR
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Post by ChrisR »

If accuracy is not important for that application, that could be a good thing.
Yes, though chances are that you'd get 500 identical! :roll:
The cytometer just needs a heavy cover, to sit firmly and not bend with "capillary suction" while cells are counted. But not another microscope slide because that would hit the objective.
Last edited by ChrisR on Tue Jan 01, 2019 11:10 am, edited 1 time in total.
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Lou Jost
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Post by Lou Jost »

If it is possible to correct for cover-glass mismatch this way, it would greatly facilitate epi-lighting as well, if we could do without cover-slips...

Edit: Of course if that were really possible, someone would have figured it out by now and we would all know about it...

abednego1995
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Post by abednego1995 »

There's an unimplemented Nikon patent application that describes a spherical aberration compensator for both finite and infinite systems.

The embodiment in fig.3 is actually a representation of a 20x NA0.75 objective and a compensator...coincidence?

https://patents.google.com/patent/US597 ... tor&page=9

Lou Jost
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Post by Lou Jost »

What about these???? Aberration correcting plates:
https://www.edmundoptics.com/f/spherica ... ates/14001

https://www.edmundoptics.es/resources/a ... on-plates/

A bit on the expensive side. Maybe there are cheaper ones somewhere?

Pau
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Post by Pau »

Lou Jost wrote:What about these???? Aberration correcting plates:
https://www.edmundoptics.com/f/spherica ... ates/14001

https://www.edmundoptics.es/resources/a ... on-plates/

A bit on the expensive side. Maybe there are cheaper ones somewhere?
From Edmund's info:
They are excellent for correcting spherical aberrations in systems that have small fields of view.
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Lou Jost
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Post by Lou Jost »

Yes, I read that, but they don't define "small fields of view". They are pretty large filters relative to the FOV of these 20x optics...

Lou Jost
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Post by Lou Jost »

"1501-9398 and 0500-0087 are most likley the same, but with different inventory numbers by illumina for different machines."

Re-opening this thread because I have these two objectives in front of me now, along with a real Nikon 20x 0.75 VC objective.

The 0500-0087 is different from the other two, in that it has fat white seals:
Image
Image

These fat white seals suggest that this version of the 20x objective is meant for immersion. The Nikon 60x VC oil immersion objective has these seals, for example:
https://www.ebay.com/p/1304654369

On the other hand, I found an example in the scientific literature of someone using this objective in air to focus a laser beam, and calling it an "air" objective; but their name for the objective looked like it was copied from an ebay ad, so may not be reliable.

Here's a water immersion objective with similar seals:
https://www.ebay.com/itm/NIKON-CFI-Plan ... SwhJteDP3g

Is it possible that this 0500-0087 version of the 20x 0.75 objective is meant to be used with a drop of oil or water between it and the flow chamber?

Lou Jost
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Post by Lou Jost »

Hmm, I see that my Nikon 20x that I sold to ChrisR last year has the same fat white seal...yet that lens is clearly made to be used in air.
https://www.photomacrography.net/forum/ ... highlight=

Scarodactyl
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Post by Scarodactyl »

I am really curious if the two different unbranded Nikons will perform the same. I love my branded 20x and the 0500-0087 performs similarly though not quite as easy for my application (but I still need to test with an appropriate tube lens). If their 1501 is different I'd love to add one to the lineup.

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