BH2 - Binocular prism disassembly. cleaning and reassembly.

[benjinsmoka]

Hello dear microbe hunters,

i try my best to explain this well, but english is not my first language so please excuse me if i get some technical terms wrong.

I just found out about this amazing forum and am looking forward to the opportunity of knowledge exchange and learning. I will follow up with an introduction on my person soon and describe in which way i am hooked on observing little things... But right now i am absorbed by a problem concerning the prism assembly P3-P4 in a binocular head for Olympus BH2 (B2-BI unit) and hope to find help among you experienced microbe hunters. I am doing a complete teardown and cleaning of the Olympus BH2 microscope and following the manuals on alanwood.com about this matter. The problem i have seems to be very rare, so i couldn't find any precise answer for how to handle the enclosed dirt between the prisms of prism assembly P3-P4 (See figures below).

Olympus Binocular BH2-BI30

IMG_0760.JPG (94.9 KiB) Viewed 1742 times

B2-BI with prism assembly P3-P4 mounted in the middle.

IMG_0753.JPG (91.29 KiB) Viewed 1742 times

Prism assembly P3-P4

PrismAssemblyP3P4.JPG (81.34 KiB) Viewed 1742 times

Dirt between prisms - view from the front

DirtBetweenP3AndP4_TopView.JPG (85.79 KiB) Viewed 1742 times

Dirt between prisms - view from the side

DirtBetweenP3AndP4_SideView.JPG (67.72 KiB) Viewed 1742 times

Here are my thoughts on the situation:


The prisms are glued together along the edges and coated by the black shield. The dirt between the prisms is evenly spread and looks like a crystallisation product or maybe fungi although i seriously doubt the latter. The rest of the binocular head doesn't look like it had an accident wich could explain this kind of pollution.

I don't know, maybe during manufacturing the prisms are glued together along their common surface, or have an layer of some substance between them? Possibly immersion oil for optical reasons (this i couldn't find out in the web, are the prisms "dry-mounted" together or is there some layer of substance in between?). This substance could have gotten bad over the year or have been exposed to a solvent which lead to this unpleasant contamination inside the prism assembly.

Anyway, I really hope you can help me with this problem!

Questions:
- How would i detach the prisms from each other? The glue looks yellowish like epoxy, would i use a heat-gun or scrape it of?
- Any solvents you recommend to clean them?
- Do the prisms get dry-mounted or is there something supposed to be in between them?
- Which kind of glue would i use to rebuild the assembly? A thick and fast hardening glue maybe?
- Any recommendations on techniques for perfect alignment while gluing?

I know thats a lot questions for a newbie, but i am really passionate about learning every aspect of microscopy and be immensely grateful for any help.
Soon i'd love to share some of my projects and contribute to this nice community.

Cheers from Berlin,
alex

[dtsh]

Hello Alex,

The prisms don't normally come apart as far as I know, or at least I don't think any manufacturers intend for it. It may help if you search for "beamsplitter" as I believe that's a more common term for it. As I'm sure you know, it's design is to divide an incoming light source into two equal (usually) paths of 50% each, one typically straight through the splitter and the other at 90 degrees. Thankfully beamsplitters are plentiful and available in a dizzying array of sizes so if may be simpller to replace than to repair. I believe many have a coating on the internal 45 degree face to facilitate the even division of the incoming light, so disassembly may damage that coating (if it exists)

[deBult]

Seller has a lot if parts: this may be a replacement.

https://www.ebay.nl/itm/153927613619

[benjinsmoka]

Thanks for the replies guys,

i will still try to fix it myself, just to satisfy my curiosity
I am just waiting for my heat gun. I will keep you informed..

chears