Two Illuminators and a Microtome

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desertrat
Posts: 243
Joined: Thu Apr 05, 2018 1:06 am
Location: Idaho

Two Illuminators and a Microtome

#1 Post by desertrat » Sun Apr 22, 2018 10:41 pm

Here's the haul from my most recent Ebay bottom trawling expedition about 2 weeks ago.
Lamps_micro.jpg
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From left to right above:

a. A complete A/O 370 illuminator. A previous owner had taken the condenser lenses out and replaced the outer large lens backwards. The convex surface was rubbing against the iris blades, and jammed the iris. Tried loosening the screws holding the cover plate on and some of blades popped out of their holes. So I got to take it all apart and put the blades back in one by one. After about half an hour of tinkering and finagling, got it all back together the right way and cleaned the condenser lenses which were filthy. The little handle for the iris got broken off in shipment (was intact in the auction photo), but enough of the broken shaft is still protruding to adjust the iris.

b. A 370 illuminator missing the condenser head with iris, and missing the thumbscrew that locks the focusing mechanism (such as it is).

c. A A/O 880 clinical bench microtome, complete with both crank handles. One or both of these is usually lost.

I really didn't need these. I already have a 370 and 735 illuminators, and a couple of microtomes. It all began innocently enough. I was browsing listings on Ebay, just window shopping, when I saw this listing for $25 buy-it-now and $31 shipping. I just couldn't resist at that price. When they arrived, there was an interesting (to me) discovery. One of the illuminators was equipped with an E26 (medium Edison screw) socket, like the unit I already have. The other one had a bayonet mount A/O 602 lamp just like a 735 illuminator, shown below.
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Closer examination showed this one had an E26 to BA15S (medium Edison screw to medium single contact bayonet) adapter screwed into the lamp socket. Below Left to right:

a. The lamp socket adapter.

b. A collar that fits over the bayonet socket.

c. An original A/O 602 lamp. I now have two of these, but don't use them because they might have value to a collector since they haven't been made for decades.

d. A modern replacement, a type BMY projector lamp. The pear shaped bulb is much smaller, but in every important aspect it is identical to the long out of production A/O lamp. The shape and structure of the filament assembly is identical, the height of the filament assembly above the lamp base is identical, and the voltage and power ratings are identical. I'm using these BMY lamps in both my adapter equipped 370 and its more refined cousin the 735, and as far as I can tell they perform identically to the original lamps.
602_BMY.JPG
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The 370 illuminator with the E26 base came with the original tubular 100w lamp which in theory would give it the same illuminating power as the later 735. These lamps have probably been out of production longer than the A/O 602. Sadly this one was burned out. However the standard base makes possible a lot of experimentation.
Lamp_exp.JPG
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Above left to right:

a. The original 120V, 100W tubular lamp

b. A 40W frosted tubular lamp available locally. I find the 40W lamp is about right for a binocular microscope, and a similar 25W lamp is about right for a monocular instrument. I was using a 25W lamp in my new purchase but it burned out. These won't give true Kohler illumination, but are handy and give a nice, evenly illuminated field even on low powers.

c. Searching for a replacement, a found this frosted 40W appliance bulb in the household box of light bulbs. It's a bit too bright for the monocular microscope I'm using to test these, but otherwise fits.

d. A 60W halogen lamp bought locally, and found in the light bulb box. It produces almost as much light as a standard 100W tungsten lamp. Too bright to try with a microscope, I tested it by wearing an arc welding helmet and looking directly into the lamp condenser and adjusting the focus. Because of the single vertical tightly coiled filament, it doesn't work quite as well as the original lamp, but true Kohler can be achieved. Even with the adapter and projector lamp, it's very difficult to get completely even illumination in the field of a 10X objective, and with the screw base halogen lamp it's probably only a little worse. The condensers in these lamps have too much spherical aberration to get even illumination with low power objectives. The condenser in my 735 lamp has the same problem.

e. A tubular 60W clear lamp I bought on Ebay for testing. This one probably isn't available locally. The comments for the 60W halogen lamp apply here, except it's not quite as bright.

f. A compact tubular halogen type JDD lamp bought on Ebay for testing. These could be promising. They're available in power ratings from 50W to 250W. According to drawings I've seen, the tightly coiled vertical filament has larger diameter coils, and might do a better job of illuminating the whole field. I ordered a 100W clear lamp from Ebay, and the seller shipped me a 150W frosted lamp. :roll: I'll probably just keep it and try it for dark field work, and get a clear one later for testing.

Next up in the experiments is try the clear halogen lamp plugged into my antique Powerstat variable transformer and try to set it up for Kohler. Turning it down to where it doesn't blind me will result in an orange light source, but I can see if it's going to work for Kohler.

At the psneeley A/O site, there is note on the lamps for the 370 illuminators. Some have been found with a screw base socket, others have the bayonet socket. I now think all of these left the factory with screw base sockets, and some were fitted later with the bayonet adapters. These adapters can be found online. There is one on Ebay, but the ceramic insulator is too long, I think, and there may not be enough vertical adjustment in the lamp holder and the lamp might sit too high. I found another one online but not on Ebay that looks like it should work, but didn't save the link. If anyone is really interested I can try to find it again.
Last edited by desertrat on Mon Apr 23, 2018 3:09 am, edited 1 time in total.
Rick

A/O 10 Series Microstar
A/O 4 Series Microstar
A/O 4 Series Phasestar
A/O 4 Series Apostar
A/O Cycloptic Stereo
Several old monocular scopes in more or less decrepit but usable condition

einman
Posts: 1508
Joined: Tue Feb 24, 2015 1:03 am

Re: Two Illuminators and a Microtome

#2 Post by einman » Sun Apr 22, 2018 11:52 pm

The microtome is a find!

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coominya
Posts: 279
Joined: Sun Mar 11, 2018 11:33 am
Location: Brisbane Aust

Re: Two Illuminators and a Microtome

#3 Post by coominya » Mon Apr 23, 2018 3:23 am

Agreed. Good buy

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ebenbildmicroscopy
Posts: 130
Joined: Sun Jul 23, 2017 8:57 pm

Re: Two Illuminators and a Microtome

#4 Post by ebenbildmicroscopy » Sat Jun 23, 2018 12:06 am

That 880 microtome is indeed quit a score. I have one of them in addition to the large AO 860 sliding, sledge type and a couple of the AO 820 rotary style. These days, almost all microtomes work by a chopping motion of passing the specimen over the cutting edge. If you carefully watch as the 880 makes a slice, due to the length of the arms that pivot the knife holder, you will notice there's an arc to the path of the blade - makes for a beautiful clean "slice"! Gorgeous, simple machine!!
JeffO, aka "Ortho amore"
Leitz Ortholux I
Leitz Orthoplan
Leitz Macro-Dia Device
Zeiss GFL
Zeiss Standard
Zeiss Photomicroscope III
Zeiss OPMI 6S
B&L Stereozoom and Balplan

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