Modification Report of the Olympus CX31 by Dr. T

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We received a modification report from user Dr. T regarding the Olympus CX31 microscope. The CX31 is an infinity-corrected optical system microscope equipped with the latest UIS2 optics. Unfortunately, obtaining information on recent Olympus (now EVIDENT) microscopes is quite challenging. Even downloading manuals requires entering personal details, such as your name and email address, and then waiting for a download link via email. However, despite multiple attempts, I have never received any emails, which raises concerns about the handling of my personal information.

In this context of scarce information, Dr. T has implemented modifications to the CX31, including adding a darkfield observation setup and installing a trinocular head from the BX series.

To perform darkfield observation with the CX31, a darkfield condenser is required. While the standard brightfield condenser of the CX31 appears to have a filter holder similar to the one on the CH2 condenser (which accommodates a blue filter), the part that looks like a filter holder is fixed and cannot be removed. As a result, unlike the CH2, it is not possible to set a darkfield filter into the "filter holder."

If the part indicated by the arrow is removed, the diaphragm blades will fall out. Removing the part that appears to be a filter holder on the CX31 condenser causes the diaphragm adjustment ring to detach, resulting in the diaphragm blades falling off—a frustrating design feature.

In contrast, on the higher-end CX41 model, sold alongside the CX31, this same part functions as a filter holder, allowing a darkfield filter to be set for darkfield observation. However, the filter holder for the CX41 condenser cannot be installed on the CX31 condenser. While it would be ideal to use the CX41 condenser on the CX31, Dr. T has modified the CX31 condenser to secure the diaphragm adjustment ring and prevent the diaphragm blades from falling out. This modification successfully enables the part that appears to be a filter holder to function as an actual filter holder.

Use a pin vise to drill three screw holes in the bottom of the CX31 condenser.

Attach thin bolts to the three screw holes. This prevents the diaphragm adjustment ring from falling off.

A darkfield filter was set into the filter holder of the modified CX31 condenser, completing the darkfield observation setup.

Instead of using a genuine filter, a darkfield filter from Small World Laboratory was used. The genuine filter, designed for the CX41 condenser, does not fit properly. While the C-series condensers starting with the CH model were characterized by having functional filter holders, the CX31 unfortunately lacks this feature. However, this limitation was brilliantly resolved through Dr. T's modification.

Dr. T also shared test photos taken with the setup, showing marine sand observed under darkfield. The sand consists of fragments of coral, shells, and foraminiferal shells, characteristic of tropical beaches. The images have a stained-glass-like appearance, beautifully conveying the atmosphere of a white sandy beach through the microscope.


Microscope: Olympus CX31 with Modified Condenser
Darkfield Filter: 8 mm by Institute of Small World
Objective Lens: 4x
Relay Lens: Olympus PE3.3x
Camera: Sony α6300

Microscope: Olympus CX31 with Modified Condenser
Darkfield Filter: 8 mm by Institute of Small World
Objective Lens: 10x
Relay Lens: Olympus PE3.3x
Camera: Sony α6300

The photos were captured using a modified setup. The images were taken with Sony's APS-C format mirrorless camera, the α6300. To attach the camera, a trinocular head is required. The CX31 that T acquired originally came with a binocular head. However, T owns a BX50 microscope with a trinocular head and mounted this head onto the CX31 for photography.

Since the specifications for attaching the heads are compatible between the CX and BX series, the trinocular head from the BX50 was mounted without any issues.



The images were captured using the following setup:

  • Sony α6300
  • Camera adapter by Institute of Small World
  • Olympus U-SPT camera port adapter
  • Olympus relay lens
  • BX-series trinocular head
  • CX31 microscope base

Olympus's latest microscope models have lowered the stage position for easier observation and significantly changed the condenser design. However, T's testing has confirmed that the specifications above the stage remain unchanged.

Summary:

  1. The CX31 condenser does not have a filter holder.
  2. The filter holder from the CX41 condenser cannot be attached to the CX31 condenser.
  3. BX-series heads can be mounted on the CX31 base.

This information should help avoid unnecessary purchases. Thank you for sharing this valuable insight!


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