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DATE: c. 1968




Nikon HP McArthur-type Microscope
HP phase rings HP phase rings
HP stage HP focus control


This microscope is of the McArthur type with a folded compact optical path for inverted slide viewing. The body is quite similar to a Nikon 35 mm camera body.

Light enters from above, either directly or by reflection. The mirror can be directed to admit an external light source or light from the built-in bulb projecting at an angle from the top of the condenser arm. The mirror has not only an adjustable angle, but also can rotate, with a stop for the front-most position where it can be directed to reflect the light from the built-in source.

HP phase ringsHP phase rings The phase rings, which are permanently installed and factory aligned, are changed by rotating the elliptical housing. One ring is labeled for use with the 10X or 40X objective, the other for the 20X or 100X. In addition, a neutral position has no phase ring, allowing brightfield illumination.

There is no iris diaphragm on this HP (handheld phase) model. Beneath the phase rings is a condensing lens that can be changed from a low power to high power by sliding a small knob on the arm forward or backward. Unlike the original McArthurs, the arm of this microscope on on a hinge and can therefore be lifted up to give easy access to the stage.

HP stage The stage is of the 'traversing' or 'gliding' type; not quite a full mechanical stage, but allowing minute movements of the slide. The stage plate moves forward or backward on greased rails, while left-right movement of the slide is under two small rubber rollers which are held on the slide by tiny springs. These tiny springs are exposed, and can easily to lost if the operator is unaware and/or careless. At least one known example of this microscope had a geared adjustment for these rubber rollers making the right-left movement fully mechanical. There is a thin plate below the stage rails which can be slid out to better access the objectives. It also had a thin plastic cover to completely protect the inside mechanism when not in use.

Unlike the original McArthur design, where objectives are changed by sliding their single rectangular housing in or out, the Nikon uses a rotating turret which rotates around a horizontal axis via a control accessed from the front of the instrument. This turret holds up to three special miniature objectives. There is a slot on the side of the microscope which facilitates placing a drop of oil on the oil immersion objective before it is rotated to contact with the slide.

HP focus control This microscope, because of the inverted slide position, insures the surface of the slide is always in the same plane, regardless of slide thickness; just like the original McArthur model, this eliminates the need for coarse focus. Unlike the original McArthur models, the focusing control is oriented with its axis of rotation in the vertical plane. This focus control is not quite as precise as the McArthur design. There is a lever underneath it, which when slid to the right locks the fine focus arm in a position for traveling.

As in the original design, the light passed through the objective enters a prism and is reflected up at the back of the instrument. The eyepiece is of standard size, however it has a threaded area just under its upper half to allow it to be secured to the eyepiece housing without the worry it would fall out if the microscope was not in an upright position. The chrome-plated sleeve which houses the eyepiece is removable.

In front of the eyepiece is the battery compartment. The door to the batteries is one of the few plastic parts. A knurled screw is used to lock the battery compartment. The bulb is housed in the top of the arm at an upward angle. The switch is at the bottom of the right side of the microscope near the front. On the front of the instrument, near the bottom is a fitting for external power; this recepticle is identical to many which are used for an external flash unit for 35 mm cameras. The quality of the optics of this microscope are superb.


This inverted portable compact microscope design originated with John McArthur in the 1930's and was repeatedly improved for the next sixty years or more. The final version of the original McArthur microscope was made by Kirk & Sons about 1993. A discussion of this type of instrument and its history along with other examples and references is found on this website.


This is the phase contrast version of the famous Nikon H inverted McArthur-type microscope. The phase contrast version is quite a bit less common than the brightfield version. Because the phase ring adjustment is performed at the factory, condensers for phase contrast vs. other applications are not interchangeable. Although there is a brightfield setting (no phase ring) on this condenser, there is no iris diaphragm. This contrasts with the Cooke-McArthur, where the condensers are interchangeable and the phase ring alignment does not need to be adjusted in the microscope because of a finer mechanism locating the objectives under the light path. Other differences include the different mechanisms for changing objectives (turret instead of sliding rails), and the ability to raise the arm of the Nikon. Although the electrical components are all integral to this model, the original McArthurs have a removable electric illumination unit. Taking all the differences and options into consideration, I personally prefer the Cooke-McArthur.

I would like to thank Dr Yuval Goren for allowing me to reproduce his images of my Nikon HP here, and for his kindness in selling me this microscope.

Nikon HP McArthur-type Microscope

Nikon HP Portable Microscope