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Bright-field microscopes have low apparent optical resolution due to the blur of out-of-focus material; Bright-field microscopes typically produce low contrast with most biological samples, as few absorb light to a great extent. Samples that are naturally colorless and transparent cannot be seen well, e.g. many types of mammalian cells.
The same cells imaged with traditional bright-field microscopy (left), and with phase-contrast microscopy (right) Phase-contrast microscopy is particularly important in biology. It reveals many cellular structures that are invisible with a bright-field microscope , as exemplified in the figure.
The advantages of these methods compared to normal absorption-contrast X-ray imaging is higher contrast for low-absorbing materials (because phase shift is a different mechanism than absorption) and a contrast-to-noise relationship that increases with spatial frequency (because many phase-contrast techniques detect the first or second ...
Michel-Lévy interference colour chart issued by Zeiss Microscopy. In optical mineralogy, an interference colour chart, also known as the Michel-Levy chart, is a tool first developed by Auguste Michel-Lévy to identify minerals in thin section using a petrographic microscope.
TEM Ray Diagram with Phase Contrast Transfer Function. Contrast transfer theory provides a quantitative method to translate the exit wavefunction to a final image. Part of the analysis is based on Fourier transforms of the electron beam wavefunction. When an electron wavefunction passes through a lens, the wavefunction goes through a Fourier ...
In microscopy transillumination refers to the illumination of a sample by transmitted light. In its most basic form it generates a bright field image, and is commonly used with transillumination techniques such as phase contrast and differential interference contrast microscopy.
Parfocal microscope objectives stay in focus when magnification is changed; i.e., if the microscope is switched from a lower power objective (e.g., 10×) to a higher power objective (e.g., 40×), the object stays in focus. Most modern bright-field microscopes are parfocal.
Confocal microscope images of a tomato leaf from Solanum lycopersicum. Brightfield DIC image showing guard cells and pavement cells (above). Same region showing Chlorophyll A autofluorescence with 440 nm laser excitation and far red emission (below). Microscopic images of a moss leaf from Plagiomnium undulatum.