Biological Microscope Phase Contrast

Biological Microscope Phase Contrast

Biological microscope phase contrast is a technique for observing organisms.biological microscope phase contrast It enhances the contrast between the specimen and background by creating constructive interference between the light rays that pass through the microscope. The method relies on two optical processes: phase-shifting and focusing. In both cases, the light rays must have different phases and amplitudes, and the specimen's light source must be focused on the conjugate area of the phase plate.

The intensity of a biological microscope's phase-contrast images is related to the refractive index of the specimen and the length of the optical path.biological microscope phase contrast The intensity of the specimen's light source can approximate relationships between structures, such as their sizes and shapes. Internal cellular organelles, for instance, tend to have a higher density than their cytoplasm, and so they appear as darker objects compared to the background. In all phase-contrast images, however, there are optical artifacts. Extended specimens often show a large amount of fluctuation in contrast. These images may also be affected by the symmetry of the specimen.

The relative phase shift between the two objects depends on the differences in their amplitudes. If the difference is negligible, no contrast is generated, and the object remains transparent and undetectable against the background. The opposite effect occurs in negative phase-contrast, in which the particle wave has a greater amplitude than the surrounding wave. However, the negative phase-contrast image is not as obvious. The vector diagram of negative phase contrast shows the direction of the surround wave vector turning 90 degrees clockwise.

In addition to the DM dark-mode positive phase-contrast objective, Nikon also offers the apodized variant of this technique. These objectives contain a secondary neutral density ring, which reduces halo artifacts. The DM dark-medium positive objective is ideal for specimens with a small phase difference. The BM bright-medium negative objective is especially suitable for visual examination of bacterial flagella.

Both negative and positive phase-contrast images contain artifacts called halo and shade-off. Figure 8 shows the intensity profile of an extended specimen with a high refractive index compared to the surrounding medium. A positive phase-contrast specimen shows a bright halo around the specimen, while the negative phase-contrast image has a dramatic shade-off effect. This contrast-contrast image contains a halo that surrounds a low frequency image detail.

The advantage of biological microscope phase-contrast over bright-field imaging is that it can reveal the cellular structures of an organism without staining them. Moreover, it does not require the use of dyes or chemicals, which can damage live specimens. So, the use of phase-contrast microscopes is widely available to researchers. They have several advantages over bright-field imaging. The bright-field images can show details of the nuclei, whereas phase-contrast images show different structures without the need for staining.

MT5310H laboratory grade upright microscope is a perfect example of a Brightfield/Phase-contrast optical system. Its design also makes it possible to study specimens with high magnifications. And MT5000 Series microscopes offer a very good cost-to-performance ratio. The MT5310H is available in three models - Epi-fluorescence, Brightfield, and Polarized light.

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