what is a "a two-channel condenser"?

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dolmadis
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what is a "a two-channel condenser"?

Post by dolmadis »

I came across this reference whilst searching for another subject.

https://www.sciencedirect.com/science/a ... 2753901633

Whilst I am intrigued I have not purchased a copy of that part of the 1953 paper.

My guess is that there is nothing new here that it is not already being used by a member/reader on this board.

But what is a "a two-channel condenser"?

BR


John

Smokedaddy
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Post by Smokedaddy »


dolmadis
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Post by dolmadis »

Very interesting condenser. Thanks for posting it JW.



BR


John

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Post by Ichthyophthirius »

Hi John,

The paper is very difficult to read as it uses almost none of the usual terms in microscopy; almost impossible to understand.

The author's point is that his design is NOT a two-channel condenser. He describes a two-channel condenser as follows:

"A two-channel condenser is generally used for optical staining of microscopical preparations. Staining occurs when light reaching the preparation at different angles is diffracted (after having passed through two differently coloured filters in the two channels). Two cones of rays of different colours are produced. One forms a solid centre, the second a surrounding hollow. In this way large angles are formed between rays of different wavelengths. Since smaller angles seem preferable in this connection, the two-channel principle has been abandoned."

"Optical staining" in this context is colour contrast in transmitted illumination.

I can't tell if the "two channels" are separate light paths or if they are created by field stops (both options were available at the time). However, it essentially sounds like a version of Rheinberg illumination. https://www.olympus-lifescience.com/en/ ... rheinberg/

Regards, Ichty

dolmadis
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Post by dolmadis »

Hi Ichty

Thank you so much for researching this encounter further and with deductions coming up with a reasonable conclusion.

As much as our interest goes a Dead End but I thank you again for looking into it.

BR

Smokedaddy
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Post by Smokedaddy »


dolmadis
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Post by dolmadis »

Very interesting to me. Thank you.

John

zzffnn
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Post by zzffnn »

I agree with Ichty in that the "two channel condenser" sounds like condenser capable of providing Rheinberg illumination.

That Lambda condenser linked by JW sounds like an oblique condenser with iris that can be decentered. Though it is hard to tell for sure, without seeing it exact mechanism/optical diagram.
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Smokedaddy
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Post by Smokedaddy »


zzffnn
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Post by zzffnn »

:twisted: ^ That is simpler than I thought and no better than my DIY oblique filter + achromat condenser. I am surprised they could publish a paper with such old and commonly used technique. Granted, that journal is not a high impact journal to begin with.
Selling my Canon FD 200mm F/2.8 lens

dolmadis
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Post by dolmadis »

Smokedaddy wrote:Image
Thanks to JW for providing the paper.

Reading the caption to the image above I note that the condenser design incorporates "a built-in positive accessory lens between the relief and iris diaphragms. Apart from collimating the light beam, the lens brings the two diaphragms optically closer together, thus enhancing the quasi-three-dimensional (pseudorelief) effect in the images and improving viewing field homogeneity"

Has anyone seen a lens deployed between the diaphragm and a "oblique filter" in any previous condenser design or since?

Is the the "USP" which is giving more than just the oblique filter?

Has anyone any recommendations please for a lens that can be easily acquired for a DIY test of the arrangement?

Could it be the lens that is found on many abbe condensers for use with low power objectives as suggested in the paper?

Thanks

BR


John

dolmadis
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Post by dolmadis »

Smokedaddy wrote:... maybe this?

http://www.lambda.cz/en/rchcondenser.html

-JW:

We are sorry but RCH condenser is not available untill further notice.

Regards,



F.Herza

LAMBDA PRAHA Ltd.

gpmatthews
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Post by gpmatthews »

Reminds me of the Goerz condenser I worked on a while back:

http://www.photomacrography.net/forum/v ... php?t=8709
Graham

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