Differences and similarities between phase contrast microscope, inverted microscope and ordinary optical microscope
Phase contrast microscope, also known as phase contrast microscope. Because light passing through a transparent sample produces a small phase difference, which can be converted into changes in amplitude or contrast in the image, allowing for imaging using the phase difference. It was invented by Fritz Zernike in the 1930s while studying diffraction gratings. Therefore, he was awarded the Nobel Prize in Physics in 1953. Currently widely used to provide contrast images for transparent specimens such as live cells and small organ tissues.
Confocal microscope: It is an optical imaging method that uses point by point illumination and spatial pinhole modulation to remove scattered light from the non focal plane 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 onto the observed object through a lens. If the object is precisely at the focal point, the reflected light should converge back to the light source through the original lens, which is called confocal, abbreviated as confocal. A confocal microscope adds a dichroic mirror to the reflected light path, which deflects the reflected light that has already passed through the lens in other directions. At its focal point, there is a pinhole located at the focal point, and behind the baffle is a photomultiplier tube (PMT). It can be imagined that the reflected light before and after the detection light focus cannot be focused on the small hole through this confocal system and will be blocked by the baffle. So the photometer measures the reflected light intensity at the focal point. Its significance is that a semi transparent object can be scanned in three dimensions through a moving lens system. This idea was proposed by American scholar Marvin Minsky in 1953, and it took 30 years of development before using laser 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 illumination system are reversed, with the former below the stage and the latter above the stage. Easy to operate and install other related image acquisition devices.
An optical microscope is a type of microscope that uses optical lenses to produce image magnification effects. The light incident from an object is magnified by at least two optical systems (objective lens and eyepiece). Firstly, the objective lens produces an enlarged real image, which is observed by the human eye through an eyepiece that acts as a magnifying glass. A typical optical microscope has multiple interchangeable objectives, allowing the observer to change the magnification as needed. These objectives are usually placed on a rotatable objective disc, which allows different eyepieces to easily enter the optical path by rotating the objective disc. Physicists discovered the law between magnification and resolution, and people realized that the resolution of optical microscopes has a limit. This limit of resolution restricts the infinite increase of 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, usually no more than 0.3 microns. If the microscope uses ultraviolet light as a light source or the object is placed in oil, the resolution can be improved. This platform has become the basis for building other optical microscope systems.
