Need help about an old Bausch & Lomb microscope: condenser alignment, model, and illumination questions

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uski
Posts: 10
Joined: Sat Feb 18, 2023 2:31 pm
Location: California, USA

Need help about an old Bausch & Lomb microscope: condenser alignment, model, and illumination questions

Post by uski »

Hi,

I recently acquired an old Bausch & Lomb microscope, mostly for fun (it was cheap, and yes I am starting to go too deep into this hobby... :lol:)

I have some questions:
- Does anyone know what model it is? I don't know why microscope manufacturers of that era had the terrible habit of never putting a model number on the body...
- There are two housings for the lamp, one with a lens and one without. What is the purpose of each?
- I understand that this has Köhler illumination, but the condenser is not aligned (X/Y). I can't find what screws to turn to align it, and I am worried about starting to turn random screws as I do not want to put anything else out of alignment. Does anyone know which screws I should turn?
- Looks like it can accept some accessories. There is a slot for filters right below the condenser. I was able to find a 12.5x eyepiece too. Any other interesting accessory?

Here are some pictures:

Light with 2 housings, with/without lens:
blm_light.jpg
Microscope front:
blm_front.jpg
Microscope right side:
blm_right.jpg
Condenser front:
blm_cond_front.jpg
Condenser right side:
blm_cond_right.jpg
PS: Quick note, that thumb screw on the right side doesn't adjust anything. It seems to lock something in place, but I cannot figure out what, as everything in the condenser is stuck in place with or without that screw :?:

Thanks!

Tom Jones
Posts: 326
Joined: Sat Jan 31, 2009 2:05 am
Location: Crestline, CA

Re: Need help about an old Bausch & Lomb microscope: condenser alignment, model, and illumination questions

Post by Tom Jones »

I just finished cleaning and lubricating 16 of these things (all surplus from a So Cal university and donated to the Microscopy Society of Southern California for refurbishment) for donation to a local high school class.

I have the model name/number at my office/lab but I'm stuck at home for a few days thanks to a bit more snow than I'd like. I believe it's a B&L Standard Teaching Microscope. It probably has a serial number from the early 1950's. The ones I cleaned up did. See: https://vademecummicroscope.files.wordp ... imized.pdf

The thumb screw on the side of the condenser holder locks the condenser in place just as you would imagine. Yours is just stuck. And I guarantee you it can be difficult to loosen up. Try heat and/or Kroil. The condenser could be stuck in the mounting ring as well.

Look at the alignment to start with. If it's pretty good, I wouldn't mess with the upper condenser. These student microscopes aren't that amenable to accurate adjustment.

The condenser alignment is done by loosening the three screws holding upper condenser (the lens in the stage) to the bottom of the stage, and moving that. Also, you can move the condenser holder alignment on the stand by loosing the four screws that hold it all together. It's not east to align. I'm pretty sure the factory used jigs to set everything up. I think Kohler is stretching the point.

The coarse focus at the top probably has grease that's turned to green wax. Not all of mine did, but the ones that had it were a pain. Some of them had been re-lubed within the last hundred years or so =P~ and probably would have worked fine. I just wanted to be sure anything I donated to a school would last quite awhile without serious maintenance. I ended up cleaning the parts with an ultrasonic cleaner and Simple Green Extreme even though I'm sure it wasn't really necessary. Reassembling it will be a bit tricky. If I were you, and I didn't do this the first time, I'd take pictures as you take it apart so you know how to put it back together. Be aware each of the screws are specific to where they go, and they look alike, but are actually different sizes so they only go into the correct place.

There are two hex socket set screws on the front of the base that will allow you to tilt the arm back 90 degrees after they are loosened. From there you can get to the fine focus screw threads and lube them. I didn't pull the fine focus out as they all worked. I just lubed them.

The illuminator is an Opti-Lume. The had different versions, but I have no clue what the differences were. They take standard 15W indicator/refrigerator bulbs that are pretty cheap. Unless you order them as microscope bulbs.

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