The last of my Olympus microscopes : an
inverted metallurgical instrument Olympus PME from the 1970s
- a fortuitous purchase.
by Daniel Nardin, France
|In August 2010, I bought a set of
equipment sold by a private seller on the French second hand web site
"Le bon coin". It probably originated from a laboratory of
One of the two main elements of the set is this inverted metallographic microscope shown right.
The design of this type of microscope incorporates a heavy and wide base which contains the electrical supply, a light metering system, a camera link and a frosted screen.
This is an Olympus PME, model sold by Olympus from 1967!
(For a short history of the firm see: http://www.olympus-global.com/en/corc/history/micro/headstand.cfm )
It is equipped with five objectives of type M from the 1970s;
the design in which Olympus used 37 mm parfocality intended for a 210 mm tube length.
The characteristics of these optics are described in the brochure below on pages 8-10:
The microscope did not look in fine condition; The original lamp, the two light and colour temperature sensors were missing.
(There was in the auction an Olympus EMM-7 cell. Probably, the former owner did not try to repair the breakdown of the base. He replaced the complex internal system by external accessories.)
|- Filters, frosted glass, canisters, but empty of objectives.||- Adaptor for dark field with three Neo lenses||- Camera backs for large film holder.|
The neutral grey filters, polarisers and light correction filters ... are useful.
This adapter is regrettably broken.
Includes a set of oblique filter stops.
A second screen is supplied.
|I have had to make some repairs (repair an ocular,
re-lubricate the movements of head, and repair the electrical connections, buy a
new bulb for £6, and to clean everything).
But fortunately, there was in the lot a separate Olympus lamp on stand; nothing was irreparable and the set was functional.
|Why did I decide to buy a set to add to my collection?
It is less efficient than my metallographic model more recent BHM (years 1980-90) with infinity optics.
This last one is more comfortable and allows in particular an easier transfer between bright and dark field by simple exchange of turret. While the black bottom of the PME requires a dismantling and the change of objective is made by slide channel.
But as an inverted model, the PME allows ready study of the surface of large subjects which are too voluminous to pass between the objective and the stage of a BHM.
( And just for this limited feature, it would not be worth buying the more recent equivalent PME3, even as a bargain on eBay and which is up to 10x more expensive!).
Here is the surface of an old vinyl record with the engraved track.
It is an example of a large subject requiring a stage without side constraints.
( Unless you wish to break the record to make the observation!)
( Image taken with the microscope PME, its objective 10x and Nikon D200)
|Another advantage of the PME is the presence of a
frosted screen for display.
It can be used by more than one viewer for assessment of a subject and to draw on tracing paper.
This kind of screen is not very bright and requires work using low ambient room lighting.
It was advantageously replaced by video systems in the 1980s.
For the demonstration shown right, I placed one screw of diameter 2 mm on the stage.
It is imaged by a low power 1,3x objective with a 7,5x projection eyepiece in the base.
A rotary dial allows magnifications to be set between 7,5 and 15x for projection on this screen.
|One noteworthy feature of the models of this
period is that their mechanics are relatively easy to understand for possible repair
(as for film cameras versus digital cameras).
The camera shutter is in a simple drawer above the four turret projection lenses of 7,5x to 15x.
|The presence of
multiple photo/viewing ports is an original feature on this model.
Besides the classic binocular head and the frosted screen, two other ports are available: one for photography and another for a photoelectric cell.
The photo port was designed for both large or small sized film; the original Olympus camera for 35 mm was not included. I have only the adaptor for a brand of reflex camera which I did not identify. I replaced it with a Nikon bayonet adaptor fixed by three screws. It allows me to take photos even if it is not parfocal with the visual field. The internal shutter does not work other than in bulb 'B' or for the 1/60th setting (and be left open using a cable release).
To note, a three position fitting allows all light to be sent to one of the three secondary ports; this design limits light loss.
|The light cell port is the same diameter as an RMS
eyepiece and gives an exploitable image, for example by a small webcam sensor
and even by a device with an APS size sensor such as my Nikon D200 digital
(But a full size capture gives circular images, of about 26 mm diameter on the sensor, example below.)
There is no parfocality either, but the focus can be made in the viewfinder.
The advantage of this port is to give an image not enlarged by projection, thus a wider field.
With a little adaptation, the old models can be used for digital images.
|In one of the boxes, there were
They are fragments of printed circuits embedded in a resin and cut and polished perpendicularly. I used them for my first tests.
I located metallic tracks deposited around holes and around the weld which fills these holes. ( D200, PME, objective 10x).
This model can be used in transmitted light. A
lamp was an option originally available for it.
|Look at these two subjects viewed from below with
a 1,3x lens in a Petri dish.
Lemna (duckweed) and small dragonfly larva (which moved during image capture);
|As I did not find an original lamp, I drilled
two holes in a wooden cube to replace the permanent lamp for reflected lighting.
(That left the base of lamp for another use.)
The device is shown right in current configuration of use, but would be more attractive with its original stem.
If readers see or have a PME out of order for sale, I would be interested in the lamp (or other accessories, as the lamp for transmitted light studies)!
Buyers of such older microscopes must be prepared
to learn: it is necessary to do odd jobs to make small repairs if we want to
take advantage of such purchase opportunities.
It is necessary to use the screwdriver, the electric tester and to use a little elbow grease for the cleaning, but the result is worth it.
It gives the owner pride to have brought out of an attic a device back to working order.
For that purpose, in spite of the rather high price of this auction lot, I am not on reflection dissatisfied with the acquisition, even if it is more interesting as collection item.
(The regular use with large subjects will be limited for me. I am a naturalist and a biologist, not metallurgist! I observe with several Olympus of the 1980s in "160mm": biological BH2, metallographic BHM = reflected light, biological inverted CK2)
September 29th, 2010
Published in the
October 2010 edition of Micscape.
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