How to Set Up Phase Contrast on Your Microscope
Phase contrast microscopy allows transparent and low-contrast specimens to be viewed with greater definition without the need for routine staining. Correct alignment of the phase objective, condenser annulus and microscope illumination is essential for achieving a clear phase contrast image.
The video below demonstrates the installation and alignment of phase contrast on a Euromex bScope microscope. The exact controls and components may vary between microscope models, but the basic alignment principles are similar on many transmitted-light phase contrast systems.
Follow the demonstration below to see how the condenser and phase rings are installed, centred and aligned.
What You Need for Phase Contrast
Phase Contrast Alignment – Step by Step
- Focus the specimen using normal transmitted light. Set up Köhler illumination where your microscope supports it.
- Select the required phase objective. For example, a 10x, 20x or 40x phase objective.
- Select the matching condenser annulus. The annulus position must correspond to the phase objective in use.
- Insert the centring telescope. This allows you to see both the condenser light annulus and the phase ring inside the objective.
- Centre the condenser annulus. Use the phase condenser centring controls so the illuminated ring is concentric with the objective phase ring.
- Remove the centring telescope and refocus the specimen. A correctly aligned system should now provide improved contrast in suitable transparent specimens.
Common Phase Contrast Problems
| Problem | Check |
|---|---|
| Poor or uneven contrast | Check that the condenser annulus is correctly centred on the objective phase ring. |
| Very dark image | Confirm that the correct annulus has been selected for the objective. |
| Phase effect disappears when changing objective | Select the matching phase annulus for the new objective. |
| Image lacks detail | Recheck focus, illumination alignment, condenser position and phase ring centring. |
Explore Microscopes & Phase Contrast Support
Need a suitable microscope or help setting up phase contrast? Browse our microscopes and inverted biological microscopes, or contact Auckland Scientific for guidance on matching phase objectives and condenser annuli to your instrument.
Phase contrast availability and optical compatibility vary by microscope model and configuration.
Auckland Scientific provides microscope application support, servicing, training and technical advice. If you are having difficulty setting up phase contrast, we can help.
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