Similarities and differences between phasecontrast, inverted, and standard light microscopy
These types of microscopes are all optical microscopes, which use visible light as a detection method, which is different from electron microscopes, scanning tunneling microscopes, atomic force microscopes, etc.
Specifically:
Phase contrast microscope, also known as phase contrast microscope. Because light will produce a slight phase difference when passing through a transparent sample, and this phase difference can be converted into a change in amplitude or contrast in the image, so the phase difference can be used for imaging. It was invented by Fritz Zelnick in the 1930s when he was studying diffraction gratings. Therefore, he won 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 organs and tissues.
Confocal microscopy: It is an optical imaging method that uses point-by-point illumination and spatial pinhole modulation to remove scattered light from non-focal planes of the sample. Compared with traditional imaging methods, it can improve optical resolution and visual contrast. The detection light emitted from a point light source is focused on the object being observed through the lens. If the object is exactly at the focus, then the reflected light should converge back to the light source through the original lens. This is the so-called confocal, or confocal for short. The confocal microscope adds a dichroic mirror to the optical path of the reflected light, which refracts the reflected light that has passed through the lens in other directions. There is a pinhole at its focus. Just 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 light focus passes through this confocal system and cannot be focused on the small hole, and will be blocked by the baffle. So what the photometer measures is the intensity of reflected light at the focus. The significance is that a translucent object can be scanned three-dimensionally by moving the lens system. Such an idea was proposed by American scholar Marvin Minsky in 1953. After 30 years of development, a confocal microscope that conformed to Marvin Minsky's ideals was developed using lasers as light sources.
Inverted microscope: The composition is the same as that of an ordinary microscope, except that the objective lens and the illumination system are reversed. The former is under the stage and the latter is above the stage. Convenient operation and installation of other related image acquisition equipment.
An optical microscope is a microscope that uses optical lenses to produce an image magnification effect. Light incident by an object is amplified by at least two optical systems (objectives and eyepieces). First, the objective lens produces a magnified real image, and the human eye observes this magnified real image through the eyepiece, which acts like a magnifying glass. General optical microscopes have multiple interchangeable objectives so that the observer can change the magnification as needed. These objective lenses are generally placed on a rotatable objective lens disk. Rotating the objective lens disk allows different eyepieces to easily enter the optical path. Physicists discovered the law between magnification and resolution, and people learned that the resolution of optical microscopes has a limit. This limit of resolution limits the infinite increase in magnification. 1600 times becomes the magnification of optical microscopes. The highest limit makes the application of morphology very limited in many fields.
The resolution of an optical microscope is limited by the wavelength of light, which generally does not exceed 0.3 microns. Resolution can also be improved if the microscope uses ultraviolet light as a light source or if the object is placed in oil. This platform became the basis for building other optical microscopy systems.
