Stereozoom microscope repair

I know, I know, send it back to the factory or to a repair center. But that costs money, and I don't learn anything if I do that.

I have a couple of 0.7 to 3.0 Bausch & Lomb microscope pods that are messed up - - one white one that requires eye convergence for less than a foot away to superimpose the images, and a black one I just bought that is okay horizontally but has a vertical offset. They don't look like they were dropped or anything, but the left eye optical path seems different from the right eye path. It may be my imagination, but the right side of each instrument looks good.

I think just about any technician or engineer who needs to work with today's surface-mount technology needs a good zoom microscope, so there must be a lot of them around. I paid $15 for the black one today, complete with stand. Okay, I should be able to afford some repair expense to put this thing back in shape, but what's it going to go for after it's fixed - - $100? Can I get it repaired for $85? I don't think so. And I Google-searched all over for some hints as to how to adjust or repair this brand of microscope, but there's not a single post that I could find that was any help. I guess all the repair techs have signed a non-disclosure agreement or something.

Getting down to business, I opened up my black $15 microscope and found a series of mirrors in the section that allows interpupillary adjustment, and two movable lenses on each side in the zoom section. The mirrors all appear to be positioned by contact with machined surfaces on pivoting aluminum castings. It doesn't look like these can move around unless one breaks loose from the glyp they put around the edges of the contact areas. Looking into the empty eyepiece holes, the left eye sees a bright elongated spot (8 to

10% of aperture area) outside the aperture at about 10:00 at all zoom settings that is not present in the right eyepiece hole - - looks like a sneak path or a chip out of a mirror. The image offset of the left when eyepieces are in place is about 1/6 of a field diameter low compared to the right, and could be converged with eyesight set for 6 ft away, if the vertical offset were not present. This offset is exactly the same at all magnifications. The white microscope behaves exactly the same at all magnifications, also.

In the zoom section, turning the zoom control rotates a pair of cam shafts grooved for pins that drive Nylon pads along guides. Each lens is fastened to its Nylon pad by a couple of screws, and it appears possible to adjust lens tilt by loosening the screws a bit. I have resisted the temptation to see what happens when the screws are loosened, but is this the only adjustment for optical convergence we have? It looks pretty sloppy and difficult to control.

So have any of you dug into your microscope and figured out how to fix it? Do any of you with B&L training care to guide an old EE to make something good out of the junk he finds at a flea market?

Thanks for all your help,

Chuck, w6pkp

Reply to
Chuck Olson
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I don't know about the Bauch & Lomb models, but the old Vickers 'Zoomax' could give vertical displacement if the rotating eyepiece turret was not returned to exactly the correct position before locking it up.

Before taking your instrument apart, just check to see that the turret hasn't been turned a few degrees by mistake.

~ Adrian Tuddenham ~
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Adrian Tuddenham

I have the same microscope. The deposits on the objective lenses is the solder flux condensing. Just take it off with flux cleaner.


Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs (among other things)

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Boris Mohar

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douglas dwyer

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