Illumination on Zeiss Standard 14

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georg
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Joined: Mon Sep 20, 2021 12:16 pm

Illumination on Zeiss Standard 14

#1 Post by georg » Mon Sep 20, 2021 12:36 pm

Hi,

I have probably a rather unuasual question: I recently got my hands on a Zeiss Standard 14 body which I am currently in the process of cleaning/servicing. The microscope body is fully functioning, however, the illumination unit is only partly complete. The base has the diaphragm and 90 degree mirror for Köhler illumination similar to this example,
Image
however I'm missing the light tube and/or external light source. This is so far not a big issue as I'm planning to convert the scope to LED illumination anyway, but I supposedly need additional optics in between the LED chip and the 90 degree mirror. I googled a bit around an found this drawing
Image
which I guess shows the light path from the Zeiss Standard. From what I understand the light from the lamp enters the mirror parallel which is somehow achieved by the three lenses directly after the lamp but I'm puzzled why there are three lenses and how to find their respective properties? Has anybody any idea how to (optically) construct such an LED lamp (mechanical/electrical construction is not the problem here). There are some LED conversions documented on the web but they all rely on the Zeiss optics and just replace the bulb.

Thanks,
Cheers,
Georg

Hobbyst46
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Re: Illumination on Zeiss Standard 14

#2 Post by Hobbyst46 » Mon Sep 20, 2021 10:33 pm

is the dark tube within the yellow frame just an empty metal tube ? no lenses ? because normally that is indeed the collimator shown in the scheme of the optical path. Should contain lenses.
BTW the mirror is a 45 degrees mirror.
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Zeiss base.jpg
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PeteM
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Re: Illumination on Zeiss Standard 14

#3 Post by PeteM » Mon Sep 20, 2021 10:38 pm

As Hobbyist said. This tube should have all the optics you need. Just put a LED die of about the same size and at the same position as the tungsten filament and you should be good.

georg
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Joined: Mon Sep 20, 2021 12:16 pm

Re: Illumination on Zeiss Standard 14

#4 Post by georg » Tue Sep 21, 2021 7:49 am

Sorry for not expressing myself clear enough. The black tube (and the lamp housing) is exactly the part I'm missing. The microscope only has the mirror (which is 45 degrees, you are right). The picture I included was just for illustration how it should look like.

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75RR
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Re: Illumination on Zeiss Standard 14

#5 Post by 75RR » Tue Sep 21, 2021 8:30 am

.
Always best to show the microscope you have if you can.

This document shows what you need and how to connect them if you want the same arrangement shown in your image.

The 60w illuminator can be adapted for LED

https://www.dropbox.com/s/m31nnua9czlfl ... r.pdf?dl=0

https://www.microscopy-uk.org.uk/mag/ar ... ersion.pdf
Last edited by 75RR on Tue Sep 21, 2021 8:55 am, edited 1 time in total.
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Adam Long
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Re: Illumination on Zeiss Standard 14

#6 Post by Adam Long » Tue Sep 21, 2021 8:41 am

Georg,

I would just try it without until you can source one, I suspect you will be able to get perfectly acceptable results. Before I sourced a bulb for mine I just shone an LED headtorch through the back - well out of position from where the design expects it. The tube does contain at least one lens and a diffuser but the Standards with built-in illumination just have a halogen bulb where the mirror is (and a diffuser just below the field diaphragm). There is a slight improvement in illumination with the bulb in the rear tube but the main improvement is the diffuser is well out of focus.

georg
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Re: Illumination on Zeiss Standard 14

#7 Post by georg » Tue Sep 21, 2021 9:07 am

Just for clarification (but I guess it was clear now), this is the actual base

Image
It was in parts for cleaning which was why I didn't just put up a picture.

I was more thinking along the lines of 3D printing a custom part that holds the LED + heatsink, a lens and a diffuser and my question was what type of lens or lenses I would need for that. From the beam path diagram I have in my first post I would have started with a simple achromatic lens assembly of the right diameter (about 25 mm) and put the LED chip in the focal point, but I'm not sure if this is correct.

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