Olympus EHT - small blue-grey filter in turret?

[Beekeeper]

I've just aquired (for a jar of honey!) an Olympus EHT of 1973 vintage (has original inspection cert). It is generally in pretty good shape and clean with the exception of a small blue-grey filter that may be made of some sort of mica-like material sandwiched between two pieces of plain glass and sits in the bottom of the turret asembly. This looks to have some fungal growth on that will not simply wipe off. My question is what is the purpose of the filter and any ideas if it can be replaced?

Thanks!

Beekeeper

[MicroBob]

This will be a polarizer. When you put one polarizer onto the light outlet in the base and one under the binocular tube you block all light if you align them right. Then bifringent objects (that turn the polarisation plane) will become visible. (Sugar crystals in honey?)
If you don't use polarisation you would use a blue filter on the light outlet to keep IR light off your eyes and get a more neutral light.

Bob

[75RR]

Welcome Beekeeper,

I've just aquired (for a jar of honey!) an Olympus EHT

That is a pretty good deal!
Do post a photo of it in the My microscope section

[PeteM]

A mix of ammonia and hydrogen peroxide will often remove fungus. Any etching will remain, but it might help clear the view through your polarizer. As others have said, you'll need one over the field (bottom) lens as well.

There are other options to replace the filter as well.

[Beekeeper]

Thanks folks, that's very helpful and yes, indeed, fructose and glucose crystals in honey samples are on the list to be photographed - though it's mainly pollen and various bits of bees at the moment. Its good to know that I can remove the duff filter for normal use. I have the original blue filter that slots into a holder just below the condenser. Unfortunately the only bits missing from the original kit are the four photo eyepieces but I can't complain at the price.

And RR75, I'll pull together a My Microscope post too.

Thanks again, Beekeeper.

[MicroBob]

Some 3D-cinema glasses are polarizers with a retarder and work quite well for non critical polarizing applications when you get the orientation right.
The eyepieces should fit to the objectives so it would be ideal to buy Olympus ones of the finity era.

[Hobbyst46]

The eyepieces should fit to the objectives so it would be ideal to buy Olympus ones of the finity era.

If the objectives on this microscope are the short barrel (the original focal length for these scopes), the appropriate photo eyepiece is the FK type, for example FK2.5.