Inexpensive home-made top illumination for Olympus VMZ

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Hobbyst46
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Inexpensive home-made top illumination for Olympus VMZ

#1 Post by Hobbyst46 » Sat Dec 04, 2021 8:18 pm

My olympus VMZ stereo has a sub-stage makeshift riser, in which a home-made LED transmitted light source had been installed. Yet the VMZ is designed for optional top illumination from the original halogen sub-stage light source, via an opening in the base, a collimating lens and an adjustable inclined mirror. To utilize these, I chose to add a separate LED lamp inside the base, and position it directly under the opening.

Some time ago these (or similar) car LED lamps were mentioned on the forum, they were listed on eBay:

2 x White DC12V 3W 18mm Push Snap in Eagle Eye Car LED DRL Light Slim Black 12V.

I found that this "lamp" can be nicely push-fitted into the barrel of common 23mm OD eyepieces and be supported and coaxially aligned on the flat rims of the inner diaphragm aperture. So I sacrificed an old nondescript eyepiece without lenses and converted it into an LED lamp housing. That lamp serves as top illuminator for the VMZ, as shown in photo 1.
1) eagle's eye LED within barrel inside microscope base. 1 LED, 2 eyepiece barrel, 3 opening in stage.jpg
1) eagle's eye LED within barrel inside microscope base. 1 LED, 2 eyepiece barrel, 3 opening in stage.jpg (42.86 KiB) Viewed 1066 times
Top illumination using the built-in collector and mirror is shown in photo 2. A long pass filter laid on top of the opening blocks light of 420nm and below (the LED is 6500K I think). No transmitted light is used. The specimen is a pile of diatoms on a black tape stuck to a slide. Above it - a mechanical finger (a metallic rod, its tip carries a glass fiber). This illumination mode serves for general purpose.
2) Top illumination setup - slanted top beam. 1 Collimator, 2 slanted mirror, 3 420nm long-pass filter, 4 slide, 5 glass fiber holder, 6 diatom pile.jpg
2) Top illumination setup - slanted top beam. 1 Collimator, 2 slanted mirror, 3 420nm long-pass filter, 4 slide, 5 glass fiber holder, 6 diatom pile.jpg (89.94 KiB) Viewed 1066 times
Note, that a focused image of the LED itself shows three intense violet spots on yellow background. Hence some defocusing would be in order. I did not use a ground glass filter, to avoid losing brightness.

Photo 3 shows an alternative side illumination: a small hollow metal cube that carries a mirror at 45 degrees and a single lens collimator. This illumination is better (brighter) for handling diatoms on the slide.
3) Top illumination setup - side beam.jpg
3) Top illumination setup - side beam.jpg (64.92 KiB) Viewed 1066 times
Photo 4 shows the specimen under this illumination. Photo 5 shows a caught diatom on the fiber.
Note: Photos 4 and 5 were taken with a hand-held phone camera over the eyepiece.
4) Open diatom pile on a dark slide in air.jpg
4) Open diatom pile on a dark slide in air.jpg (83.84 KiB) Viewed 1066 times
5) Diatom attached to glass fiber tip.jpg
5) Diatom attached to glass fiber tip.jpg (23 KiB) Viewed 1066 times
This illumination is just a very inexpensive lamp for viewing and working under the microscope, not quality photography.

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