Phase Contrast

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Phase Contrast

a method of producing images of microscopic objects whose structural elements have refractive indexes and optical absorptivities that differ by such small amounts that the elements are indistinguishable in other methods of observing and producing images in a microscope. However, such structural elements introduce light-wave phase shifts that may differ appreciably from one another, producing variations in phase that cannot be detected by either the eye or a photographic emulsion.

Phase contrast consists in the conversion of the phase variations, by means of an optical accessory, into variations in the intensities—that is, in the amplitudes—of the light waves. Such amplitude variations can be detected by a photodetector. Phase contrast was developed by F. Zernike in 1935. (SeeMICROSCOPE: Methods of illumination and observation [microscopy].)

REFERENCES

See references under MICROSCOPE.

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No references found			These can be quantified with phase contrast (PC) velocity encoding, which provides an instantaneous measure of fluid velocity, and can be used to provide velocity-time and flow-time curves through the valves and the great vessels, thus allowing calculation of pressure gradients. Cardiovascular magnetic resonance imaging--a pictorial review by Dahya, Vijay; Spottiswoode, Bruce S. / South African Journal of Radiology The phase contrast microscopy is a technique used for a light through a translucent specimen and changed the contrast in the image. The Various Classifications of Microscopes by Justin Martin / General interest community The so-called phase contrast CT pictures show even smallest variations in the specimen's bone density with extremely high precision: Cross-sections of cavities where bone cells reside and their roughly 100 nanometer-fine interconnection network are clearly visible. New Computer-Tomography Method Visualizes Nano-Structure of Bones by FARS News Agency			pharyngo-tonsillar diphtheria Pharyngobdellae pharyngology pharyngoscope Pharyngoscopy Pharynx Phascogale Phascolarctos Phase Phase Advancer phase age phase alternating line phase angle phase behavior phase boundary phase change phase change cooler phase change disc phase change memory Phase Characteristic phase coherence phase comparator phase conductor phase conjugate system phase constant Phase Contrast phase control phase converter phase correction Phase Correction Unit, Telegraph phase crossover phase delay phase detector phase deviation phase diagram Phase Difference phase discriminator phase distortion Phase Encoded phase encoding phase equalizer phase equilibria Phase Equilibrium phase excursion phase factor Phase Fixation phase front phase function phase generator phase inequality phase integral			Phase boundary phase change phase change phase change phase change phase change cooler phase change cooling phase change disc phase change disk phase change drive Phase Change Dual-Layer Phase change heat pump Phase change heat pump Phase Change Materials Phase change memory phase change printer Phase change ram phase change recording Phase Change ReWritable Phase Characteristic Phase Code Interval phase coherence Phase comparator Phase Compensation Instability phase conductor Phase Conjugate Circuit phase conjugate system Phase constant Phase Contrast Phase Contrast Magnetic Resonance Imaging phase contrast microscope phase contrast microscope phase contrast microscope Phase contrast microscopy Phase Contrast Optical Microscope Phase control Phase control Phase Conversion and Step Down Phase converter Phase converter Phase converters Phase converters Phase convertor Phase convertor phase correction Phase Correction Unit, Telegraph Phase Correlation Motion Estimation phase crossover Phase delay Phase delay Phase delay line Phase delay line Phase descendante Phase Detection Auto Focus Phase detector Phase detector phase deviation Phase diagram Phase diagrams

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