Tag: cell and its discovery

The standard oil immersion objective lens used in light microscopy typically provides a magnification of 100x.

In electron, fluorescent, and ultraviolet microscopes, the light or radiation used is often invisible to the human eye, requiring a fluorescent screen or photographic plate for detection.

Ultraviolet light is invisible to the human eye, so direct observation through an eyepiece is not possible; the image must be captured on a photographic plate or digital sensor.

Fluorescence microscopy relies on the excitation of fluorophores using high-energy light, typically UV or blue light, to emit visible light. Therefore, it utilizes both UV rays for excitation and visible light for the resulting emission.

Standard glass lenses absorb ultraviolet light, making them unsuitable for UV microscopy. Quartz and fluorite are transparent to UV radiation, so lenses made from these materials are used instead.

A stop disc (or dark-field stop) is placed in the condenser to block the central light rays, allowing only oblique rays to strike the specimen. This creates the dark-field effect where the specimen appears bright against a dark background.

A stop is an opaque object that blocks the central light when placed underneath the stage condenser. This also causes light to scatter in all azimuths, resulting in a cone of light that allows for dark field observation.

Atomic force microscopy (AFM) is a type of scanning probe microscopy capable of imaging surfaces at the atomic level, providing detailed topographical information about biological molecules.

Phase Contrast Microscope was developed by Zernike. The microscope has a phase plate and an annular diaphragm. They bring about changes in light rays passing through the specimen producing differences in light intensity. Denser parts alter path of light more than the thinner parts. This produces varying contrast for different regions. Hence, staining is not required and the difference between denser and lighter parts of the specimen is revealed by the phase difference. The microscope is useful in the study of small living organisms, living cells, constituents of living cells, effect of various factors over living structures, and study of various cellular events like behaviour of chromosomes during mitosis and meiosis, spindle formation, cytokinesis, pinocytosis, phagocytosis, cyclosis, glandular secretions, spermatogenesis, oogenesis etc.

Fluorescence microscopes use UV or blue light to excite samples and require specific filters (like excitation and emission filters) to isolate the wavelengths of light, which are often referred to as complementary filters.