BX51 Metallurgical DIC, Brightfield & Darkfield

Read the Edited Video Transcript for ‘BX51 Metallurgical DIC, Brightfield & Darkfield’

Hey, this is Chad with Munday Scientific and Microscope Marketplace. Today, we’re going to talk about an Olympus BX51 metallurgical microscope.

We typically focus on biological microscopes, but today we’re covering a materials (metallurgical) microscope. This particular unit has just been sold and is equipped with:

Brightfield
Darkfield
DIC (Nomarski Differential Interference Contrast)

This setup is commonly used for applications such as silicon wafers and materials inspection, where enhanced contrast is critical.

Trinocular Head and Light Path Control

This microscope features a trinocular viewing head with standard light path options:

All the way in: 100% of light to the eyepieces
Middle position: Light split between eyepieces and camera
All the way out: 100% of light to the camera

We have additional videos covering this in more detail, but today we’ll focus on contrast methods.

Reflected Light Illumination

This microscope uses reflected light illumination, meaning:

The lamp house is located on top
Light passes through the illuminator
It reflects off a mirror and is directed down onto the specimen

This is ideal for opaque samples, such as metals or wafers.

In contrast, transmitted light systems shine light through the specimen from below.

Brightfield vs. Darkfield

The microscope includes a brightfield/darkfield selector lever.

Brightfield: Standard illumination
Darkfield: Enhanced contrast with a dark background

Switching between the two dramatically changes how the specimen appears.

Objectives and Nosepiece

This microscope uses Olympus Plan Fluor (FL) objectives designed for metallurgical work.

Objective Set

5×
10×
20×
50×
100×

Each objective is labeled “BD”, meaning it supports both:

Brightfield
Darkfield

These are high-quality objectives, commonly used in materials science applications.

DIC Prism Selection

The microscope includes a DIC slider system.

You’ll see markings such as:

U Plan FL (current configuration)
LM Plan (long working distance objectives)

For this setup:

The U Plan FL setting must be engaged
If using LM objectives, the slider position would need to be changed

Setting Up DIC (Differential Interference Contrast)

To achieve proper DIC imaging, several components must be correctly aligned.

Step 1: Bring Specimen into Focus

Focus the specimen using brightfield first.

Step 2: Insert Analyzer and Polarizer

Both the analyzer and polarizer must be engaged.

At this point, the image may not change significantly.

Achieving Extinction

Next, rotate the analyzer.

As you rotate it, the image will become darker
When the field becomes completely dark, you have reached extinction

This means:

The polarizer and analyzer are crossed
Their optical axes are aligned properly

This step is critical—DIC will not work without extinction.

Engaging the DIC Prism

Once extinction is achieved:

Insert the DIC prism slider
The image will now appear more three-dimensional
Contrast and color effects will become visible

Adjusting DIC Contrast

You can fine-tune the DIC effect by:

Rotating the prism adjustment knob

This changes:

Contrast
Color interference patterns
Apparent depth (3D effect)

Important Notes for DIC Operation

For proper DIC imaging:

The polarizer must be in
The analyzer must be in
The poles must be crossed (extinction achieved)
The correct DIC prism must match the objective
The illumination must be properly aligned

If any of these are incorrect, the image will not display proper DIC contrast.

Demonstrating the Effect

If you remove either:

The polarizer, or
The analyzer

The DIC effect disappears, and the image will look completely different.

This highlights how important proper alignment is.

Final Thoughts

The Olympus BX51 with DIC is a powerful tool for materials analysis.

It allows users to:

Enhance contrast dramatically
Visualize surface features
Achieve a pseudo-3D effect on flat samples

This makes it especially valuable for wafer inspection and industrial applications.

Where to Buy & Contact Information

If you have questions about this microscope or similar systems:

Website: microscopemarketplace.com
Email:
Phone: 919-775-5596

Closing

If this video brought you value, please like and subscribe.

Thanks for watching!