Comments on the Columbia Instruments FM 600 Field Microscope article

[lorez]

I found the article Columbia Instruments' FM 600, A Unique US Army Field Microscope to be most interesting and inspiring and I tip my hat to those who worked on this project.

To organize my comments on the I have copied several portions of the article. Each of the copied excerpts is numbered and in quotes. My comments are my opinions, based upon my experiences with these microscopes.

1 “Columbia Instruments initially considered a different microscope for the core of the FM 600, one made by Southern Precision Instruments (SPI), but decided instead to use Swift components for the FM 600.” This was probably a wise choice. At the time the quality of the Swift products were much better in all regards than those of SPI.

2 “One of the earliest FM 600s Columbia Instruments built, had a horse shoe base and used non- DIN ((Deutsches Institut für Normung), non-infinity corrected, objectives.” This was probably the Swift model M950.

3. “The scope first produced for evaluation originally had plan achromats, but as these would have cost too much to supply in large quantities, the objectives were changed to standard DIN objectives, with working distances of about 45mm.” Other than the “flatness” of the field there is no difference in the image quality of the two styles. At the time the plan lenses were significantly more expensive than the basic achromat. I may point out that this lens does not pass the NIOSH (The National Institute for Occupational Safety and Health) standard for resolution necessary for the asbestos abatement industry.

4. “The coarse adjustment pinion gear required extensive attention to detail. It needed to be machined appropriately to allow sufficient space for the substage, and thus easier access to the controls of the mechanical stage. If the slide stage became too dry, it would stress the mechanical stage, and this stress might be transferred to the pinion sleeve. Therefore, two extra 6-32" Allen head, hex, set screws were used to secure the sleeve. This means hex keys are required for assembly or disassembly of the FM 600.” I would like to see some close-up photos of this area as I wonder about what they mean. The lubricants that Swift (or Kyowa who actually made the microscope) had a fairly long functional life span before they dried to the extent of being problematic.

5. “The base plate was made of aluminum and so required a separate spraying with a vinyl wash before paint would adhere.” I wonder why they went to the trouble of making their own base plates. I think the standard plate available was almost the exact same. The one I have looks to be identical. Maybe the dimensions are a bit different, but still, I wonder.

It seems that the M600 is now replaced with a much inferior model for the sake of some basic digital capabilities. That’s sad.

lorez

[lorez]

I just thought of something else.

We spend a lot of time on this group discussing such things as plan-apo objectives and high NA condensers and which bit matches which other bit, but a point in favor of this field microscope is that it is of modest pedigree and yet certainly of sufficient quality to meet the needs of the military medical corps for twenty-five years.

lorez

[apochronaut]

That all depends on what you intend to do with the microscope. A military field microscope is not required to provide imaging beyond a basic standard ; they aren't looking for too much because anything major would be medevaced, so any average achromatic microscope with an average condenser can meet the optical requirements. More importantly, what it is intended to do is, be small enough to fit in a backpack, not fall apart during transport, use little energy and be capable of securing that energy from various sources and be relatively inexpensive( from the military's point of view, which is albeit a distorted point of view). In this version of the U.S. Military's choice, it seems that the dual requirements of small and binocular went hand in hand, something that few microsopes combine.

[apochronaut]

My bulb burned out. Time to become a bulb manufacturer.

[zzffnn]

Thank you, Lorez, for the comments.

It is interesting to know that Kyowa actually made that Swift scope. I remember reading that Kyowa made a field scope similar to Tiyoda MKH as well.

Does NIOSH demands a specific lower NA limit for specific objective magnification? How did they specify resolution requirement? I am just curious.

I saw that yucky successor scope too.

[lorez]

It is interesting to know that Kyowa actually made that Swift scope

As the economy of imported microscopes evolved Swift switched production to several other Asian manufacturers.

Does NIOSH demands a specific lower NA limit for specific objective magnification?

I'm not sure I understand this one. The typical objectives are Olympus and Nikon 40/0.65 phase contrast.

How did they specify resolution requirement? I am just curious.

There is a test slide with several groups of parallel lines that are of diminishing size. The objective must be able to resolve to the third or fourth line group.

lorez

[Charles]

That all depends on what you intend to do with the microscope. A military field microscope is not required to provide imaging beyond a basic standard ; they aren't looking for too much because anything major would be medevaced, so any average achromatic microscope with an average condenser can meet the optical requirements. More importantly, what it is intended to do is, be small enough to fit in a backpack, not fall apart during transport, use little energy and be capable of securing that energy from various sources and be relatively inexpensive( from the military's point of view, which is albeit a distorted point of view). In this version of the U.S. Military's choice, it seems that the dual requirements of small and binocular went hand in hand, something that few microsopes combine.

With my experience as a Navy Corpsman (Medic) attached with field Marine units, portable microscopes were only used in BAS (Battalion Aid Stations) and RAS (Regimental Aid Stations) mainly for diagnosis of infectious diseases. One usually would not carry a microscope into battle since most battle injuries does not require microscopy. The microscopes in the aid stations were used for basic urinalysis, CBCs (to rule out appendicitis or other infectious disease), Gram stains for Venereal disease and Darkfield for detecting spirochetes for syphilis. All of this can be detected with just Achromatic objectives and do not need any other higher resolution or Plan lenses except the 100X which usually required an iris for Darkfield. Anything else requiring microscopy or other diagnostic equipment was sent to the rear to a field hospital.

[apochronaut]

From the information the maker gave for the micscape article, it seems that the overriding specification for this instrument, to set it apart from it's predecessor was that it be binocular and modeled on a conventional lab instrument. The other specifications were mostly met by the AO 3050 and optically it was probably about as good. AO , no doubt bid on this contract but they would have had to convert the 3050 to a binocular head and that conversion alone, would have gobbled up some cash plus, the folding feature definitely was not modeled on a lab microscope.
It also had to fit in a back pack along with a centrifuge and chemicals and have an air release valve.
The FM 600 is definitely a diminutive binocular microscope, the smallest I've ever seen by far. It weighs 17 2/3 lbs. in it's case and about 2/3 of that is the case and power supply. The AO 3050 weighed 13 and some in it's case.

[Drew]

lorez,

Thanks for the thread. After reading the article here in microbehunter and a similar one by the same author in micscape, I bought one of these FM 600 off ebay. The case looks like it has been around, but the microscope is in real good shape. I asked the seller if he knew any of its history and he said that he got it from somebody who owed him money.

Charles,

Appreciated your post. From the article, I figured this microscope was designed to be used by SF Medics. It appears from the number sold that it was adopted by the whole Army.

apo,

The Bulb, mine burns but I better get a spare ready. Mine appears to be like the halogen bulbs with the leads instead of a flashlight type krypton soldered in.

[charlie g]

Thanks for this thread and all the posters comments,lorez. I really appreciate the insights of Charles regarding the function of these stands with respect to battle zones. It makes sense to me that just as a 19th century mine medic need adept amputation skills and equipment...a forward battle field microscope is not utilized by the medic at the front.

Over a decade ago, then forum head, Gordon C., commented in another great microscope forum, on the pre antibiotic era life and death choice of: to do appendectomy vrs. less invassive medicine...really had those vintage Spencer monoc stands utilized by the properly skilled 'country doctor' for CBC, etc.. I really appreciate Charles for giving insights to use of these field stands...I always wondered about these WWII era military field microscopes and their work life.

charlie guevara