You have seen many Biology books to know that the microscope have helped us catch a glimpse of organisms, cellular matters, and parts of our body that cannot be seen by the naked eye. The microscope, after all, can magnify objects through the use of specialized lens and light. But what about objects that are transparent? How have scientists have come up with images of organisms that do not absorb light? How about those that are naturally colorless? The answer lies in a microscope called phase contrast.



Introduction to Phase Contrast Microscopy

Our eyes can only see colors of the visible spectrum and the differing intensities of light. Objects that absorb light are easy for us to observe because of these biological capability. Even if the objects are very tiny, it's still possible for us to see them if we use a microscope. However, transparent and colorless objects, such as bacteria, sperm tails, flagella, and some parts of the cell, cannot be seen clearly under typical light microscopes. This is because light travels through these objects in a way that our naked eye cannot detect. Light passes through these specimens, called phase objects, slower and they are shifted. This change in phase cannot be detected by our eyes. This is why it would be impossible to study these objects clearly.

In the 1930s, a Dutch scientist named Frits Zernike developed the phase contrast method. He observed that it is possible to increase change in phase or shift in these transparent objects by half a wavelength. This was done by the use of rings etched onto plates of glass. The method resulted in patterns of interference. These patterns, in turn, made the details of the phase objects darker than the background. The contrast is increased and they become visible to the naked eye.

Phase Contrast Microscopy Today

Zernike received a Nobel price for inventing the method. It was a well-deserved accolade because he has revolutionized the way microscopy works today. Because of his invention, we have been able to properly observe objects that would otherwise have been impossible to analyze under a normal light microscope.

If it weren't for this method, for example, we would never have known how cell division works. Without phase contrast microscopes, transparent and colorless objects are stained so that they can be observed under the microscope. This staining method makes them absorb color but it alters their components. It can kill some phase objects, too. Incidentally, killing phase objects also makes them more visible but it becomes impossible to observe their processes. Killing them often defeats the purpose of observation. With this technique, it is possible to observe living cells and how they divide.

Used with other modern devices, this kind of microscope has even made it possible to see the internal structures of these phase objects. Post-processing and other enhancement devices can now make us see what goes on inside transparent and colorless organisms. They used to be beyond the reach of technology but a genius changed that. Science and mankind has definitely benefited from this incredible invention.

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