Mastering the Olympus BH2 Microscope

View the Edited Video Transcript for ‘Mastering the Olympus BH2 Microscope’

Hey, this is Chad with Munday Scientific. Today, we’re going to take a look at the Olympus BH2 microscope, a classic instrument that remains popular among microscope users.

This is an oldie but a goodie. The BH2 was one of the microscopes that helped establish Olympus as a major competitor in the clinical microscopy market, competing with manufacturers such as Leitz Wetzlar.

Even today, the BH2 is an excellent microscope.

This particular microscope was recently purchased by a customer and has been fully refurbished. We’re going to go over some of its features, discuss the different components, and demonstrate how to disassemble and reassemble it.

Trinocular Head and Camera Adapter

We’ll start with the trinocular head.

This microscope is equipped with a V-clamp and a Diagnostic Instruments camera adapter. The adapter has a focusable adjustment and is secured with two screws.

When these microscopes were originally introduced, 35 mm film cameras were commonly used for photomicrography. Today, different adapters can be installed to accommodate modern C-mount microscope cameras.

The trinocular head operates very similarly to those found on newer Olympus BX-series microscopes.

It has a pull rod that controls the light distribution between the eyepieces and camera port.

Depending on the position of the pull rod, you can direct the light entirely to the eyepieces, split the light between the eyepieces and camera, or direct 100% of the light to the camera.

This particular head has been completely relubricated by an authorized Olympus service technician, so all the adjustments operate smoothly.

Eyepieces and Diopter Adjustments

The microscope has 10X eyepieces with a 20 mm field of view.

One side of the trinocular head has a built-in diopter adjustment, allowing you to focus that eyepiece independently.

The other side has a focusable eyepiece with its own adjustment.

You’ll notice a small locating pin on the focusable eyepiece that fits into a corresponding notch in the eyepiece tube. This keeps the eyepiece properly positioned and allows you to adjust its focus without the entire eyepiece rotating.

It’s a convenient feature that makes focusing easier.

Standard Binocular Head Option

Another common configuration for the Olympus BH2 is the standard binocular head.

To remove the trinocular head, simply loosen the retaining screw and carefully lift the head away from its dovetail mount.

The standard binocular head attaches in the same location.

Many BH2 microscopes were originally supplied with this conventional binocular configuration.

Both head styles work well, and the choice depends on whether you need a camera connection.

Nosepiece and Objective Removal

Unlike some newer Olympus microscopes, the nosepiece on this BH2 is not designed to be removed as a separate assembly during routine maintenance.

To remove an objective, first lower the stage completely.

This provides additional clearance and helps prevent accidentally scratching an objective or damaging a slide.

Once the stage is lowered, carefully unscrew the objective from the nosepiece.

Reinstallation is just as simple. Thread the objective back into its position and make sure it is securely seated.

Phase Contrast Objectives

This particular BH2 is configured for phase contrast microscopy.

You’ll notice that one of the objectives is marked SPlan 10X PL.

The PL designation identifies it as a phase contrast objective in this configuration.

Phase contrast objectives work with corresponding annular diaphragms in the condenser to enhance contrast in transparent specimens.

A standard brightfield objective generally won’t have the same phase designation.

Mechanical Stage and Slide Holder

Next, we’ll remove the mechanical stage.

Start by lowering the stage completely and making sure there’s enough clearance between the stage and the objectives.

The slide holder can be removed by loosening the two knurled screws that secure it to the stage.

One common issue with older Olympus BH2 stages involves the plastic racks used in the mechanical stage movement.

Over time, these racks can develop small hairline cracks as the plastic ages.

When this happens, you may notice that the stage movement feels uneven, almost as though it’s going over a speed bump.

On this microscope, the original racks have been replaced, and the coaxial stage controls have been completely relubricated.

As a result, the stage movement is smooth and feels like new.

Replacement stage racks are available through our online store.

Phase Contrast Condenser

Underneath the stage, we have a phase contrast condenser.

The condenser has different phase annulus positions that correspond to the microscope’s phase objectives.

For example, the 10X phase objective uses its matching 10X phase position. The same principle applies to the 20X, 40X, and 100X phase objectives, using the appropriate matching condenser settings.

The condenser also has a zero position, which is used for standard brightfield observation.

Properly matching the condenser annulus to the phase objective is essential for achieving the intended phase contrast image.

Field Diaphragm and Daylight Blue Filter

The Olympus BH2 has a field diaphragm that is used when setting up proper illumination.

It also has a daylight blue filter.

Because this microscope uses a halogen illumination system, the light naturally has a warmer, slightly yellow appearance.

The daylight blue filter helps reduce that yellow hue and produces a cooler, more neutral appearance when viewing specimens.

Halogen Lamp and Socket

The BH2 uses a halogen illumination system, and we’ve covered bulb replacement in another video.

This particular microscope has a new bulb installed.

The lamp assembly also includes a reflector that helps direct light into the microscope’s illumination system.

Olympus produced different BH2 configurations, including the higher-powered BHS version, which uses a 12V, 100W illumination system.

These microscopes provide excellent illumination and remain very capable instruments.

Coarse Focus Tension Adjustment

Another important feature of the BH2 is its coarse focus tension adjustment.

The tension collar allows you to control how freely the stage moves when using the focus controls.

If the tension is too loose, the stage may gradually drift downward under its own weight.

If the tension is too tight, focusing can become unnecessarily difficult.

To adjust the tension, use the appropriate tool in the adjustment collar and rotate it in the required direction.

Moving the adjustment one way increases tension, while moving it the opposite way reduces tension.

The goal is to achieve smooth focusing while maintaining enough resistance to prevent the stage from drifting.

Focus Stop Adjustment

The BH2 also includes a focus stop mechanism.

This allows you to establish an upper limit for stage travel.

Once the stop is set, the stage cannot be raised beyond that predetermined position without releasing or adjusting the stop.

This is especially useful for preventing the objective from accidentally contacting a slide.

The focus stop and tension adjustment work together to provide controlled, predictable stage movement.

Removing and Reinstalling the Condenser

Now let’s take a look at the condenser mounting system.

The condenser is held in place by a retaining screw in the substage assembly.

Loosen the screw and carefully remove the condenser.

You’ll notice a locating pin on the condenser that corresponds with a notch in the mounting bracket.

When reinstalling the condenser, position it so the pin enters the appropriate opening.

Rotate the condenser gently until you feel it settle into its proper position.

Once it’s seated, secure the retaining screw.

The condenser is now ready to be centered and aligned.

Setting Köhler Illumination

After reinstalling the condenser, you’ll want to set Köhler illumination.

We have another video demonstrating that procedure in detail.

For this microscope, we recommend beginning the Köhler illumination setup using the 10X objective.

Proper Köhler illumination helps provide even illumination across the field of view and allows the microscope’s optical system to perform as intended.

Centering the Phase Contrast Rings

The phase contrast condenser also has small adjustment pins used for centering the phase annuli.

These adjustments are important because the condenser annulus must be properly aligned with the corresponding phase ring in the objective.

Unless you’re familiar with the phase contrast alignment procedure, it’s best not to adjust these pins unnecessarily.

On this particular microscope, the phase contrast condenser turret has been relubricated, and the phase rings have already been centered.

Everything is operating properly and is ready for use.

Reassembling the Olympus BH2

Now that we’ve reviewed the components, let’s put the microscope back together.

Reinstalling the Slide Holder

Start by reinstalling the slide holder onto the mechanical stage.

Align the mounting points and tighten the two knurled screws.

Reinstalling the Stage

Lower the microscope’s focus mechanism to provide adequate clearance.

Carefully position the stage onto its mounting surface.

Make sure the stage is sitting flush before tightening the retaining screw.

Reinstalling the Head

Next, position the trinocular head onto the microscope’s dovetail mount.

Make sure the mounting flange is properly seated beneath the retaining surfaces.

Once everything is aligned, tighten the retaining screw securely.

Always support the head until you’re certain it’s locked in place.

Reinstalling the Eyepieces

Install the non-focusable eyepiece into the tube with the built-in diopter adjustment.

Then install the focusable eyepiece into the opposite tube, making sure its locating pin fits into the corresponding notch.

Reinstalling the Camera Adapter

Finally, slide the camera adapter back into the trinocular head’s camera connection.

Position it correctly and tighten the two retaining screws.

The microscope is now fully reassembled.

Why the Olympus BH2 Is Still an Excellent Microscope

The Olympus BH2 is one of those classic microscopes that has stood the test of time.

It helped establish Olympus as a major manufacturer in the clinical microscope market, and many of these instruments are still being used today.

With proper servicing, relubrication, and replacement of worn components, a BH2 can continue providing excellent optical performance.

This particular microscope has been fully refurbished, including the trinocular head, mechanical stage, phase contrast condenser, and illumination components.

It’s a great example of how well these microscopes were originally built.

We’ll be producing more videos covering the Olympus BH2 and its various components.

Replacement Parts and Contact Information

If you’re interested in an Olympus BH2 microscope or need replacement parts, we can help.

We carry a variety of components, including mechanical stage racks, lamp sockets, condensers, objectives, and other microscope accessories.

You can find these items through our online store:

Website: MicroscopeMarketplace.com

If you have any questions, feel free to contact Munday Scientific.

Phone: 919-775-5596

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We look forward to hearing from you. Thanks for watching!