The phase contrast microscope principle is frequently used to view objects that would be otherwise difficult to see under an ordinary microscope. These objects are often transparent and wouldn’t be visible otherwise without the help of staining, which doesn’t give the most accurate picture.
Phase contrast microscopy has delivered revolutionary results in the field of cell biology. However, to properly use the phase contrast microscope technique, you must understand how it works.
In this article, you’ll learn everything there is to know about the phase contrast microscope principle.
Understanding Phase Contrast Microscopy
Phase contrast microscopy lets you observe a living cell through a special microscope. These live cells can be viewed through a special microscope called a phase contrast microscope.
This mode of microscopy and the microscope itself was invented by Dutch Physicist Frits Zernike, who was awarded the Nobel Prize in Physics in 1953.
The phase contrast microscope principle states that small changes in the light path can be transformed into differences in brightness or light intensity. However, these changes must be induced by differences in the thickness and refractive index of the different parts of an object.
The key is that these phase changes are undetectable to the human eye, but the brightness and light wave intensity enable humans to observe a living biological specimen through this microscope.
Components of a Phase Contrast Microscope
For the most part, a phase contrast microscope contains many of the same parts as an ordinary compound microscope. These parts include:
- Light source
- Condenser system
- Objective lens system
- Ocular lens system
In addition to these components, the microscopes also include a phase condenser or phase annulus to control the object’s illumination, which helps to create a hollow, narrow cone of light that illuminates the object.
There is also a diffraction plate at the back focal plane of the phase contrast objective lens to help reduce the phase of incident light.
How the Phase Contrast Microscope Principle Works
Phase contrast microscopy starts with unstained living cells. These cells absorb almost no light, which makes them impossible for the human eye to see, and even challenging to see in some microscopes.
With a phase contrast microscope, the light phase shifts are converted in a way that makes them possible to be observed as differences in image contrast. This conversion is to changes in amplitude rather than small light phase shifts.
This happens because light encounters regions in the cell with different thicknesses and refractive indexes as it passes through an unstained cell.
How to Add Phase Contrast to a Microscope
With all of this new knowledge on phase contrast microscopes, how do you use one?
Well, the good news is that you don’t have to buy a brand-new microscope for phase contrast microscopy. You can simply upgrade your current light microscope.
Adding phase contrast to your current microscope is one of the best ways to upgrade a light microscope and gain visibility into living cells. Adding phase contrast to a microscope is also cheaper than adding fluorescence or differential interference contrast.
You must, however, ensure that the phase ring aligns with the condenser annuli for phase contrast to work.
Applications of the Principle
There are many ways to use a phase contrast microscope. The most notable example is that it has substantially contributed to living cell research by allowing us to view unstained living cells in action. This also includes viewing microorganisms, thin tissue slices, and subcellular particles.
That said, there are other applications of phase contrast microscopes. These applications include:
- Generally making transparent objects more visible
- Examining intracellular components of living cells at high resolution
- Studying cell division
- Visualizing all types of cellular movement
Overall, this microscope – or at least attachments for your current microscope – is worth it.
Phase Contrast Microscope FAQs
Can phase contrast microscopy be used for live imaging?
The main advantage of a phase contrast microscope is that it doesn’t require the cells of biological samples to be killed or stained before viewing them. This type of microscope allows biological samples to be viewed in their natural state.
Is special training required?
You don’t need special training to use this microscope.
As mentioned, these microscopes are similar to most other magnification techniques, except for a phase annulus diaphragm and a diffraction plate.
As long as your microscope has these components and you’re already aware of how to use a microscope, you should have no problem with this type of scope.
Can phase contrast microscopy be combined with other microscopy techniques?
Modern phase contrast microscopes can operate in combination with other magnification techniques. These techniques include:
- Differential interference contrast
- Polarized light
See More Than Ever
To conclude, this optical microscopy technique was made to see living cells without staining and killing them. This type of microscope has significantly advanced scientific research and enabled discoveries never dreamt of before.
You don’t need special skills to use a phase contrast microscope, yet thanks to Frits Zernike, you’ll be able to see more than you could have ever imagined.
Learn about several other types of microscopes in this article.