Metallurgical microscopes

[eKretz]

I managed to run across a neat old microscope for a pittance, planning to do some examination and perhaps photos of tool edges and a few other things. It's an Olympus Vanox AHMT or AH-BT2. This one is capable of reflected Brightfield, Darkfield, polarization and DIC illumination. Are there any fellow industrial/research microscope users around that have experience with one of these? I have a few questions about some of the techniques, prisms and filters and how they're used. Also could probably use some spare parts if anybody has any for these old scopes.

 

[Milland]

Looks like a proper bit of kit. I haven't used a real metallurgical microscope since tech HS, so I'm of no help, but I hope you get it full operational.

I do have some stuff that I want to turn into hack digital microscope, but it probably won't be anywhere as good as that guy.

 

[eKretz]

I think I have most of what is needed. Got everything to do brightfield and darkfield, missing one slide-in filter for polarization and one slide-in prism/pol for DIC. Should be pretty good. I think originally these cost about as much as a nice car when they were made, so quality should be quite nice.

 

[Milland]

Post some pics when you get a camera set up.

 

[eKretz]

Will do. That is one thing I do need to get set up: a mount for the camera.

 

[Robert R]

There are a number of online interactive tutorials available describing condenser setup and polarized, darkfield, and DIC imaging techniques.

This is one of many:
Interactive Tutorials | Nikon’s MicroscopyU

There are also a number of Zeiss papers available in PDF format if you are interested in the optical theory involved. A determined internet search may also uncover the user manuals for the old Olympus microscope. The Zeiss manuals for the old Universal series microscopes are online. Zeiss, Nikon, and Olympus use slightly different approaches to DIC imaging. The important point to remember is that the objectives and their DIC sliders (prisms) need to be a matched set.

 

[PeteM]

I can likely help if you'll post some pictures of what you have -- along with any questions. Some Vanox scopes were equipped with "short barrel" Olympus metallurgical objectives and the newer (but still pretty old ones) with "long barrel" objectives with a DIN standard 45mm parfocal distance.

Yours looks to be the "later" version with all the 35mm camera controls built in. Those will be kind of annoying, but it ups the likelihood you have the newer objectives.

The typical approach to fit a camera back then was to use a 2.5x photo relay lens in the trinocular head, with proper corrections for the version of objectives, and then fit a 35mm film camera. A full frame digital camera works well -- what you see in the eyepieces is about what you get in the camera. Another easy approach is to get a third 10x eyepiece, a cell phone camera holder, and use your cell phone. Most of the newer ones take surprisingly good images - better than typical dedicated microscope cameras selling for $300 to $500.

 

[eKretz]

I have found what I believe is a basic manual but it doesn't go into much depth. I understand the basics of DIC etc. already, but as mentioned, every manufacturer is a little different in the exact setup and particulars so I was hoping someone here might perchance be a researcher or university guy and have the scoop on stuff specific to this exact scope.

Since this is reflected DIC, not transmitted, it seems that only a single prism/pol analyzer is needed to make it work in this system. As I think I understand it, the light separates/shears when going through the Nomarski prism down to the subject, then recombines on the way back up to the eyepiece. There are polarizing filters in the path, one built in on a slider in the main reflected light path and one that gets placed in above the objectives combined with the Nomarski prism slider. The objective lenses are supposed to be just regular Neo Splan infinity objectives according to the manual, no extra prisms involved. They are apparently made with low-strain techniques.

This scope has several different switchable light paths and 4 different camera ports. I think, but am not certain that the camera controls will be defunct at this point, as I believe they originally controlled Olympus cameras through the electronic lens mount interfaces. There were multiple versions of the Vanox scope, the first having no camera controls, then the three different camera control versions (AH, AH-2, AH-3). Mine is the second - and the 'T' version, which means mostly manual controls for the cameras - which is fine by me since I plan to use a DSLR that won't be controlled by the scope. There was also an 'S' version that had autoexposure and autofocus. After these microscopes came the BX scopes and the newer stuff. I also have a CX, which is a transmitted light only scope.

 

[PeteM]

You've got the reflected DIC right -- a single prism is used to shear both the epi illumination and then combine it back headed up into the eyepieces. Some Olympus generations used a single sliding prism to cover all magnifications. Other generations used adjustable prisms located on an interchangeable nosepiece. Typically, 10x, 20x, 40x, and 100x magnifications were supported with the individual prisms.

Basic setup is to get the polarizers crossed for extinction and then introduce the DIC prism into the path. If you have all-original components it should be pretty straigtforward. Where it gets complicated is if different generations have been mixed -- the proper orientations of the polarizer, analyzer, and DIC prism can then take a while to sort out.

You need to polarize the light headed down on to the specimen and then polarize (or "analyze") it again above the DIC prism. If you're missing a polarizer or analyzer, you can probably get a high quality linear polarizer and make a blackened aluminum frame for it. Even cheap circular camera polarizers can be used, but they may need to be flipped to become "linear" and they typically don't give as full extinction and as good DIC.

The Vanox is a massive scope, beautifully made, but with all sorts of camera controls that are now obsolete. Chances are you could move the optics to something like an Olympus BHM (stripped of all the now-obsolete controls) if you wanted. If yours came with a set of newer Neo Splans (chrome barrels, not black enamel with color bands) that's good news. If you have the single sliding prism setup, that's also very versatile.

 

[eKretz]

You've got the reflected DIC right -- a single prism is used to shear both the epi illumination and then combine it back headed up into the eyepieces. Some Olympus generations used a single sliding prism to cover all magnifications. Other generations used adjustable prisms located on an interchangeable nosepiece. Typically, 10x, 20x, 40x, and 100x magnifications were supported with the individual prisms.

Basic setup is to get the polarizers crossed for extinction and then introduce the DIC prism into the path. If you have all-original components it should be pretty straigtforward. Where it gets complicated is if different generations have been mixed -- the proper orientations of the polarizer, analyzer, and DIC prism can then take a while to sort out.

You need to polarize the light headed down on to the specimen and then polarize (or "analyze") it again above the DIC prism. If you're missing a polarizer or analyzer, you can probably get a high quality linear polarizer and make a blackened aluminum frame for it. Even cheap circular camera polarizers can be used, but they may need to be flipped to become "linear" and they typically don't give as full extinction and as good DIC.

The Vanox is a massive scope, beautifully made, but with all sorts of camera controls that are now obsolete. Chances are you could move the optics to something like an Olympus BHM (stripped of all the now-obsolete controls) if you wanted. If yours came with a set of newer Neo Splans (chrome barrels, not black enamel with color bands) that's good news. If you have the single sliding prism setup, that's also very versatile.

Thanks, and yes it is meant to use the chrome Neo Splans (anybody got any of those laying around, I could use a couple... ...and has a single analyzer slot with interchangeable sliding prisms and filters, along with a few other accessory slider slots. I am missing the Nomarski slider though. Looking at ebay sold items it seems that it may be within the realm of possibility to find one for a couple hundo if I get lucky. With lots of time due to the back issues and low income I'm good at biding my time, so hopefully that will happen. I only generally get about an hour at the microscope before my back is toast, so not looking to invest a fortune anyway. Recently I had a bit of setback with my back so have been doing even worse. Getting incrementally better day by day but it's slow going; been over a week and I'm still not right (back to my normal). Hoping that the flurry of upcoming doc appointments will find something fixable for once.

Being that I've got to work within those constraints I will probably leave the scope as is and allot it a permanent space on one of my workbenches. It is about 70 pounds. I should be all set to use it as-is for BF/DF/Pol.

I really like the stage with the built-in rotation, and most of the camera controls I can just ignore. It really is a beautifully made scope, from an era of very high quality.

 

[eKretz]

Man, now I just had a BX40 fall in my lap. I'm on a roll.

 

[eKretz]

Here's the new one:



Time to sell the CX and get paid for picking the BX up, heh.

 

[eKretz]

Oh, and Pete, know anyone looking for an Olympus mercury burner lamp, couple fluorescence cubes and power supply? Those came on the BX but I only want to use BF/DF/phase and maybe DIC. Keeping the URA but not gonna mess with fluorescence.

 

[PeteM]

Congrats - the BX40 is a terrific scope. You might even find yourself getting interested in things like chemical crystals under polarization?

Probably best to sell the mercury lamp and power supply on Ebay. If you don't have a brightfield reflected cube (no fluorescence filters) and want to do epi work - you might hold on to one of the cubes and strip the filters out. Just a BF cube runs around $200 - the whole scope near $2000 used.

 

[greif1]

Here is a very nice site with manuals:
Download old Olympus microscope catalogues and instruction manuals

 

[eKretz]

Congrats - the BX40 is a terrific scope. You might even find yourself getting interested in things like chemical crystals under polarization?

Probably best to sell the mercury lamp and power supply on Ebay. If you don't have a brightfield reflected cube (no fluorescence filters) and want to do epi work - you might hold on to one of the cubes and strip the filters out. Just a BF cube runs around $200 - the whole scope near $2000 used.

Absolutely. Lucky find. Apparently a lab that went out of business... Someone I know was contracted to clean out this vacated leased space, including all abandoned property. If I hadn't grabbed this it would be in a dumpster! Got a bunch of goodies with it too. Several crosshair eyepieces, spare tilting binocular head, similar goodies etc. Should make me some good money selling off the bits that are duplicate or surplus to my needs.

 

[eKretz]

So Pete, are you saying the fluorescence cubes have the same mirror setup as the brightfield cubes, the only difference being that the plain BF cube is without the front and vertical filters? Interesting. Although I wonder if I might make enough selling the fluoro cube to fund the BF cube and at the same time maybe help someone out who wants a used fluoro cube...

 

[PeteM]

So Pete, are you saying the fluorescence cubes have the same mirror setup ...

I don't have the fluorescence head on my own BX40, so am not 100% sure. I'd think so. For my Nikon E600, the cubes have pretty much the same half-mirror but with excitation and viewing filters added for fluorescence use.

Darkfield cubes are different - they need the extra aperture.

The used fluorescence stuff often doesn't bring as much money as one thinks it should. It's used mostly in biological research where various fluorescence stains are used to identify specific proteins. However, once a lab gets budget to upgrade to a newer scope, there aren't many hobbyists out there looking to do fluorescence.

And even other labs with tiny budgets hesitate to buy used fluorescence gear for various competitive bid policies and liability reasons. A past-its-date mercury lamp has a tendency to explode and turn a lab into a hazmat site. And the barrier filters degrade over time and present a risk of eye damage.

One change to that is that UV LEDs are now getting powerful enough to be quite useful, even for hobbyists. Then the risk is mainly making sure there are good barrier filters and no leaks. In addition, many labs now do all their imaging digitally. No one actually looking through the microscope.

I do have a couple Olympus epi scopes (not fluorescence, but epi brightfield, darkfield, and DIC) and those cubes seem to run near $200 each - often as much or more than fluorescence cubes with the extra filters.

 

[eKretz]

Do you know offhand which objectives the BX uses for EPI BF/DF? I assume it's not the Neo SPlans, right ?

 

[PeteM]

This catalog gives the options: https://www.olympusamerica.com/seg_industrial/files/industrial_component_guide.pdf

The Neo SPlans were a sort of transitional objective series, where the epi adapter turned something like a BH2 series finite frame into infinite optics. They're good and only cost the arm or leg of an "arm and a leg" on the used market. The newer UIS2 stuff tends to be very expensive, even used, unless you happen to luck into something.