Differences and similarities between phase contrast, inverted and ordinary optical microscopes
These types of microscopes are all optical microscopes that use visible light as a detection method, unlike electron microscopes, scanning tunneling microscopes, atomic force microscopes, etc.
Specifically:
Phase contrast microscope, also known as phase contrast microscope. Because light passing through transparent samples produces a small phase difference, which can be converted into changes in amplitude or contrast in the image, phase difference can be used for imaging. It was invented by Fritz Zelnik in the 1930s while studying diffraction gratings. Therefore, he was awarded the Nobel Prize in Physics in 1953. It is currently widely used to provide contrast images for transparent specimens such as living cells and small organ tissues.
Confocal microscope: an optical imaging method that uses point by point illumination and spatial pinhole modulation to remove scattered light from the non focal plane of a sample. Compared to traditional imaging methods, it can improve optical resolution and visual contrast. The detection light emitted from a point light source is focused on the observed object through a lens. If the object is exactly in focus, the reflected light should converge back to the light source through the original lens. This is called confocal, abbreviated as confocal. A confocal microscope adds a semi reflective mirror to the path of reflected light, folding the reflected light that has already passed through the lens in other directions. There is a pinhole at its focal point, which is located at the focal point. Behind the baffle is a photomultiplier tube (PMT). It can be imagined that the reflected light before and after the detection of the focal point cannot be focused on the pinhole through this confocal system, and will be blocked by the baffle. So the photometer measures the intensity of reflected light at the focal point. Its significance is that by moving the lens system, a semi transparent object can be scanned in three dimensions. This idea was proposed by American scholar Marvin Minsky in 1953. After 30 years of development, laser was used as the light source to develop a confocal microscope that met Marvin Minsky's ideal.
Inverted microscope: The composition is the same as a regular microscope, except that the objective lens and lighting system are reversed, with the former under the stage and the latter above the stage. Convenient operation and installation of other related image acquisition devices.
An optical microscope is a type of microscope that utilizes an optical lens to produce an image magnification effect. The light incident on an object is amplified by at least two optical systems (objective and eyepiece). Firstly, the objective lens produces a magnified real image, which is observed by the human eye through an eyepiece that acts as a magnifying glass. A typical optical microscope has multiple replaceable objective lenses, allowing the observer to change the magnification as needed. These objective lenses are generally placed on a rotating objective disc, which allows different eyepieces to easily enter the optical path. Physicists discovered the law between magnification and resolution, and it was only then that people realized that there is a limit to the resolution of optical microscopes. This limit limits the infinite increase in magnification, with 1600 times becoming the highest limit of magnification for optical microscopes, which greatly limits the application of morphology in many fields.
The resolution of an optical microscope is limited by the wavelength of light, generally not exceeding 0.3 micrometers. If a microscope uses ultraviolet light as a light source or an object is placed in oil, the resolution can also be improved. This platform serves as the foundation for building other optical microscopy systems.
