Dan M. Stump : Thesis [from 1921] : Application of Polarised Light to Resolution

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MichaelG.
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Dan M. Stump : Thesis [from 1921] : Application of Polarised Light to Resolution

#1 Post by MichaelG. » Fri Jan 18, 2019 7:59 am

For convenient reference: This is a re-posting of :
viewtopic.php?f=28&t=7008

..................................................
I have just found this on archive.org

Application of Polarised Light to Resolution [ Cover ]
or
An Application of Polarized Light to Resolution with the Compound Microscope [ Title Page ]
https://archive.org/details/applicationofpol00stum

A fascinating read, with excellent illustrations.

MichaelG.
..................................................

Hopefully, it will prompt some experimentation
Too many 'projects'

Hobbyst46
Posts: 4277
Joined: Mon Aug 21, 2017 9:02 pm

Re: Dan M. Stump : Thesis [from 1921] : Application of Polarised Light to Resolution

#2 Post by Hobbyst46 » Fri Jan 18, 2019 9:24 am

MichaelG wrote:An Application of Polarized Light to Resolution with the Compound Microscope
Thanks Michael for the link.

Downloaded for reading... and done reading (not every word, skipped math pages).

Some late night thoughts:

So Stump's idea was to illuminate the specimen with two simultaneous, perpendicularly polarized beams, obliquely aligned, spaced at ~90degree interval along the perimeter of the sub-condenser carrier.

Indeed, the diatom is a tiny diffraction grating. One more reason to be fond of it... :)

A key feature in Stump's method is that both beams must emanate from the same point source, like in interferometers. Stump used an incandescent bulb and its mirror image, somewhat like a more modern illuminator where the lamp stands in front of a mirror - Zeiss HBO for example.

His specimen was the diatom mounted in realgar. This stuff has the highest refractive index - 2.4 - so, probably it offers the highest contrast, in brightfield at least. The RI of the mountant does not appear in Stump's calculations, but low contrast might mask resolved dots. Most of us use mountants of lower RI I believe, so I wonder if Stump's demonstrated improvement of resolution can be reproduced under lower RIs.

Hobbyst46
Posts: 4277
Joined: Mon Aug 21, 2017 9:02 pm

Re: Dan M. Stump : Thesis [from 1921] : Application of Polarised Light to Resolution

#3 Post by Hobbyst46 » Mon Jan 21, 2019 9:30 pm

Hobbyst46 wrote:
MichaelG wrote:An Application of Polarized Light to Resolution with the Compound Microscope
A key feature in Stump's method is that both beams must emanate from the same point source, like in interferometers. Stump used an incandescent bulb and its mirror image, somewhat like a more modern illuminator where the lamp stands in front of a mirror - Zeiss HBO for example.
.
Just a sudden thought, this might be realized with a bifurcation optical fiber, where the common node is connected to the light source and the two other fiber ends point at the polarizers. I guess there are varios diameters of optical fibers of such configuration. The immediate advantage over the lamp-mirror arrangement is that the intensities are exactly identical, no need for tiresome adjustments.

MichaelG.
Posts: 3976
Joined: Mon Apr 10, 2017 8:24 am
Location: North Wales

Re: Dan M. Stump : Thesis [from 1921] : Application of Polarised Light to Resolution

#4 Post by MichaelG. » Mon Jan 21, 2019 10:44 pm

Good thinking !!

MichaelG.
Too many 'projects'

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