AO Spencer Series 4: Am I Missing a Mirror?

[NerdManual]

Thanks again for your help on my previous questions. Of course I have more.

I opened up the light assembly on my Series 4 to clean out the dust and corrosion. (Some unidentified liquid was spilled on this in the past and looks like it pooled in the base. It left a nice blue color around the rim though.) If you take a look at the photo below, I want to know if there should be a mirror attached to the metal trapezoidal plate (top left of the pic). The metal plate is held against the diffuser tube with springs and looks like it should reflect the light up, but there's only a black coating on the plate (could be old adhesive). If a mirror should be there I can probably find something at the art supply store, but do you have any suggestions where I should look for one that I don't have to cut to size?

[Zuul]

The color is most likely Methylene Blue that somebody spilled. My AO 10 has a very similar ring, but purple; probably Crystal Violet.

Any mirror will work, but I suspect the original was a very thin 1st surface mirror for the highest efficiency. (They have silver on the surface so the light doesn’t have to pass through glass twice as it’s reflected.). Others here will know for certain. Member Apochronaut knows a almost everything about the AO ‘scopes.

[BramHuntingNematodes]

Thorlabs sells a nice 2" round thin-coated aluminum mirror for $30 plus they sometimes send snacks with your order.

[apochronaut]

You might have a look at the inexpensive dental mirror source that I passed on to Hobbyst46 in the following thread. Last I heard he was very pleased with his results.
viewtopic.php?f=5&t=5995&hilit=dental+mirrors

[Hobbyst46]

You might have a look at the inexpensive dental mirror source that I passed on to Hobbyst46 in the following thread. Last I heard he was very pleased with his results.
viewtopic.php?f=5&t=5995&hilit=dental+mirrors

Still very pleased. Thanks again apochronaut. I sandwiched the mirror between thin plywood plates on a vice, and cut it with a hacksaw. Slowly and carefully. The trick is to use a fine pitch saw blade, like 24 teeth per inch (even better - 32 tpi).

[NerdManual]

Thank you all for the mirror confirmation and the suggestions for mirror options. I am amazed that I could get any light at all with no mirror and can only imagine how different it will be when I put one in there. This has become quite a project.

[apochronaut]

maybe the previous owner had some innovative ideas. staining the entire microscope instead of the slide; a new kind of differential staining. ....removing the mirror for dark field! not exactly what they had in mind. kind of like the proctologist that does 18 holes a day.

[NerdManual]

maybe the previous owner had some innovative ideas. staining the entire microscope instead of the slide; a new kind of differential staining. ....removing the mirror for dark field! not exactly what they had in mind. kind of like the proctologist that does 18 holes a day.

The guy I bought this scope from got it from got it at a garage sale, but I imagine it in a classroom in the late 1980s where some miscreant experimented on the scope instead of whatever he was supposed to be doing. The iris in the base was jammed tight. More dark field experiments? I took that apart this afternoon...unintentionally. I meant to just gently break it loose, but it came completely apart. Took me 45 minutes to get all the blades back in, but I got it clean and it's working now with only a slight snag when it's almost fully open.

[Hobbyst46]

...I took that apart this afternoon...unintentionally. I meant to just gently break it loose, but it came completely apart. Took me 45 minutes to get all the blades back in, but I got it clean and it's working now with only a slight snag when it's almost fully open.

Bravo. New mirror installation is easier then reassembly of the leaf aperture.