Phase+Contrast+Microscopy

=__**Phase Contrast Microscopy**__=

**Basic Description and Purpose**
====A phase contrast microscope amplifies the slight difference in the refractive index which causes the edges of cells to be highlighted. Cells then appear dark on a bright background because the thinner parts are viewed as brighter and the thicker parts appear darker. Cells can be viewed while alive in wet mounts. This is useful because cellular processes can be viewed in real time or by pictures in time-lapse. This is also good for viewing surfaces, edges, and organisms that blend into the environment (transparent, colorless, unstained).====
 * ===The phase contrast microscope works by sending two beams of light through condensers which eventually direct the light toward the specimen. The light then passes through the specimen where the beams split again and then goes through the objective toward the image plane. In the space between the specimen and the image plane the light becomes diffracted due to the molecules within the specimen being viewed. This diffracted light is what produces the image.===



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Origin and History
====Phase contrast microscopy was developed in 1938 by Frits Zernike who went on to win the Nobel Prize for his contributions in 1953. He developed the phase contrast microscope after he began noticing interference patterns with beams of light that led to contrast differences. He added pieces to the standard compound microscope to get the desired effect. The end product became the phase contrast microscope (Anderson, 2010).====

Recent Research
1. One article altered the phase contrast microscope to be able to see the organelles of Eukaryotic cells. The phase contrast mode at a photon energy around 2.5 keV allowed for 3D nanoscale imaging of the majority of eukaryotic cells (Wang, 2013). 2. A recent article viewed the Influenza A virus under the phase contrast microscope in order to observe the characteristics of the virus. This technique worked well for viewing the virus and proved its efficiency for this type of microscopy without producing artifacts (Yamaguchi, 2008). 3. Using a neutron beam the phase contrast can be used as a nondestructive method that works better than the standard phase contrast microscope. This is beneficial because of its available large beam size and the high transmission of materials which are strong absorbers for X-rays (Kardjilov, 2008).