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German Gipsplatte

Posted: Thu Nov 28, 2019 2:05 pm
by Bluelight

I am reading older german microscope litterature, and see mentions of a "Gipsplatte", not Lambdaplate / Gipsplatte Rot 1, but a "black" background plate. I think it has something to do with "Herzog's" eyepiece with build in +45, -45 degrees red plates and the so called "Gipsplatte" which gives black field in the polarization microscope.
Is it a zero degrees gipsplatte inserted to make a whole plate to insert into the optics, or something else?

Re: German Gipsplatte

Posted: Thu Nov 28, 2019 6:36 pm
by Roldorf
Strange "gipsplatte" in English means "plasterboard".

Re: German Gipsplatte

Posted: Thu Nov 28, 2019 7:07 pm
by Scarodactyl
Gips=gypsum. Drywall is made of gypsum, but so are gypsum accessory plates.

Re: German Gipsplatte

Posted: Fri Nov 29, 2019 12:30 pm
by Bluelight
Yea, I do know. My first language is neither English or German, but I can explain a bit. "Gypsum" is the litteral material they made Lambdaplates of, that is 560nm zeroth order full wave waveplates. So, I am wondering why someone would angle an zeroth order plate at zero degrees, that is equal to the axis of polarizer, or the analyser...

My theory so far, is there is simply an need to fill the physical space in the plate inserted in the microscope accessory, since you got two different thin slices of gypsum material lambdaplates, one at minus 45 degrees, other at positive 45 degrees.
I need to know, since I need to try replicating the experiment. Do it work with inserting a modern Lambda at zero degrees? If so, I can do that.

Re: German Gipsplatte

Posted: Wed Dec 04, 2019 8:15 pm
by Chris__R
Gypsum is just a convenient material for a full wave plate, as mica was for quarter wave plates.
The standard thickness was 25ยต but the retardation is proportional to thickness. Half wave plates were made from both I believe.

If you're asking what a full wave plate is for, it's eg handy for orienting yourself on the Michel Levy chart.

Re: German Gipsplatte

Posted: Thu Dec 05, 2019 10:41 am
by Bluelight
I am asking if someone knows what an "Alois Herzog" specialized microscope redplate accessory buildt-in microscope ocular, with stripe of +45 degree Red plate/Lambda, a stripe of -45 degree Red plate/lambda, and an referenced "Black background" plate named just "Gipsplatte", which is something which appear to have no strenght, function or anything whatsoever.

The black background is from crossed nicols, that is, polarization filters. The filters block light, the topmost probably is build into said "Alois Herzog" ocular.

I am fully able to rotate a plate to zero degrees, so I can do this; but is that needed to replicate an colour measurement using such an device?