Introduction
The FM mechanical stages were originally intended for use with Olympus microscopes, but two of them were supplied as part of the OM system to fit the Stage Plate 28. The Olympus OM literature only refers to the FM mechanical stage, but the illustrations all show the FM-II stage, not the original FM.
The Stage Plate 28 is made of metal, with a matt black finish, and has a central aperture 28 mm in diameter, so it can be used for transmitted or reflected light. Near the outer edge there is a threaded hole and 2 guide holes for attaching the stages.
Olympus OM Stage Plate 28
Versions
The first version, the FM, pre-dates the OM system. Two later versions, the FM-II and FM-III, were supplied as part of the OM system. The model numbers and version numbers are not marked on the Stages.
Mechanical Stage FM
The FM mechanical stage is shown in a catalogue that includes the E and F microscopes, so it may fit the interchangeable RS round revolving stage, which appears to have suitable attachment points. The same catalogue includes the HSB student microscope, which is “Designed to accept a mechanical stage, if desired”.
Olympus Mechanical Stage FM (photograph courtesy of Mark Dapoz)
It is not known if the FM fits the Stage Plate 28.
Mechanical Stage FM-II (FM-2)
The FM-II (or FM-2, US stock no. 104-135) was the first version supplied with the OM system. The Olympus literature only refers to the FM, but the illustrations clearly show the FM-II. It fits the Stage Plate 28 and enables precise positioning of subjects for high magnification work. It has a sprung clip for holding a 3″×1″ microscope slide or other objects. It was replaced by the FM-III.
There is about 53 mm movement on the long axis, via a worm drive, and the scale is marked from 40 to 102 mm. There is about 27 mm movement on the short axis, via a rack and pinion, and the scale is marked from 0 to 36 mm. On each axis there is a Vernier scale that allows measurements to be made to the nearest 0.1 mm.
Olympus Mechanical Stage FM-II
The FM-II also fits the stage plate of the BHMJ metallurgical microscope, and it was listed as an accessory for the Olympus HS, HSB and HSC microscopes.
Mechanical Stage FM-III (FM-3)
The Mechanical Stage FM-III (or FM-3) replaced the FM-II as part of the OM system. It fits onto the Stage Plate 28 and enables precise positioning of subjects for high magnification work. It has a sprung clip for holding a 3″×1″ microscope slide or other objects.
Olympus OM Mechanical Stage FM-III (on Stage Plate 28)
There is just over 50 mm movement on the long axis, via a worm drive, and the scale is marked from 40 to 100 mm. There is just over 30 mm movement on the short axis, via a rack and pinion, and the scale is marked from 0 to 38 mm. On each axis there is a Vernier scale that allows measurements to be made to the nearest 0.1 mm.
The FM-3 was also listed as an accessory for the BHMJ metallurgical microscope and attaches to the detachable stage plate. The BHMJ plate is about 110 mm diameter and so it is not compatible with the Macrophoto Stand VST-1 or with Olympus stereomicroscopes.
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Created 18th May 2001 — Updated 23rd April 2026
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