Phase-contrast microscopy is an optical-microscopy technique that converts phase shifts in light passing through a transparent specimen to brightness changes in the image. Phase shifts themselves are invisible, but become visible when shown as brightness variations.
When light waves travel through a medium other than vacuum, interaction with the medium causes the wave amplitude and phase to change in a manner dependent on properties of the medium. Changes in amplitude (brightness) arise from the scattering and absorption of light, which is often wavelength-dependent and may give rise to colors. Photographic equipment and the human eye are only sensitive to amplitude variations. Without special arrangements, phase changes are therefore invisible. Yet, phase changes often carry important information.
Phase-contrast microscopy is particularly important in biology.
It reveals many cellular structures that are not visible with a simpler bright-field microscope, as exemplified in the figure.
These structures were made visible to earlier microscopists by staining, but this required additional preparation and killed the cells.
The phase-contrast microscope made it possible for biologists to study living cells and how they proliferate through cell division.
After its invention in the early 1930s, phase-contrast microscopy proved to be such an advancement in microscopy, that its inventor Frits Zernike was awarded the Nobel prize (physics) in 1953.
Phase-contrast imaging is a method of imaging that has a range of different applications. It exploits differences in the refractive index of different materials to differentiate between structures under analysis. In conventional light microscopy, phase contrast can be employed to distinguish between structures of similar transparency, and to examine crystals on the basis of their double refraction. This has uses in biological, medical and geological science. In X-ray tomography, the same physical principles can be used to increase image contrast by highlighting small details of differing refractive index within structures that are otherwise uniform. In transmission electron microscopy (TEM), phase contrast enables very high resolution (HR) imaging, making it possible to distinguish features a few Angstrom apart (at this point highest resolution is 3-4 A).
Phase contrast takes advantage of the fact that different structures have different refractive indices, and so bend light and delay its passage through the sample by different amounts. The retardation of the light results in some waves being 'out of phase' with others, and so to the human eye a microscope in phase contrast mode effectively darkens or brightens particular areas to reflect this change.
“First, I considered the traditional inverted phase contrast microscope equipped with charge-coupled devices (CCD), but it is time-consuming to manually rename image files on a personal ...
The SI-PH PhaseCondenser has been added as an accessory option to the lineup of the ECLIPSE Si biological microscope, improving work efficiency in research and educational fields requiring Phase Contrast....
Competitors are welcome to use any type of light microscope and technique, including phase contrast, polarized light, fluorescence, interference contrast, darkfield, confocal, deconvolution, and mixed techniques.
Microscopes are optical instruments used to magnify and observe small objects or specimens that are not visible to the naked eye ...OpticalUprightInverted Stereomicroscopes PhaseContrastFluorescence Other Optical Microscopes.
This evolution in leadership aims to take the company to the next stage with the development and launch of the Van Gogh system, an advanced phase-contrast microscope that is optimized for “specimen ...
Photographers can use any type of light microscopy technique, including phase contrast, polarised light, fluorescence, interference contrast, darkfield, confocal, deconvolution, and mixed techniques, as well as record any subject matter.
Patients and their families utilizing the facilities at PhilipHealth Services may notice continued construction in areas ... New equipment for the lab includes a phase contrast microscope ... Staining often results in death or damage to cells ... ....
Prof Awadh Bihari Yadav in his lab. (HT) ... The key components of an animal cell culture facility include biosafety cabinets, CO2 incubators, single-cell counters, a centrifugation machine, and a phase contrast inverted microscope ... ....
Photographers can use any type of light microscopy technique, including phase contrast, polarised light, fluorescence, interference contrast, darkfield, confocal, deconvolution, and mixed techniques, as well as record any subject matter.
Form follows function... Choosy queen bees ... Honey bee sperm are devilishly difficult to study, even with powerful microscopes and tried-and-tested techniques such as phase-contrast microscopy, a technique that allows more contrast in a viewed sample.
The Colchester Sun
29 May 2024
The Colchester Sun
29 May 2024