Similarities and Differences Between Phase Contrast Microscope, Inverted Microscope and Ordinary Light Microscope
These types of microscopes are all optical microscopes, which use visible light as the detection method, which is different from electron microscopes, scanning tunneling microscopes, and atomic force microscopes.
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 that the phase difference can be used for imaging. It was invented by Fritz Zernike in the 1930s while studying diffraction gratings. For this 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 microscopy: It is an optical imaging method that uses point-by-point illumination and spatial pinhole modulation to remove scattered light from the non-focus plane of the sample. Compared with traditional imaging methods, it can improve optical resolution and visual contrast. The probe light emitted from a point light source is focused on the observed object through the lens. If the object is just in focus, the reflected light should converge back to the light source through the original lens. This is the so-called confocal, or confocal for short. A dichroic mirror is added to the optical path of the reflected light in the confocal microscope to bend the reflected light that has passed through the lens to other directions. There is a pinhole (Pinhole) at its focus, and the pinhole is located at the focus. Behind the baffle is a photomultiplier tube (PMT). It can be imagined that the reflected light before and after the focus of the detection light passes through this set of confocal system, but cannot be focused on the small hole, and will be blocked by the baffle. The photometer then measures the intensity of reflected light at the focal point. Its significance is: a translucent object can be scanned in three dimensions by moving the lens system. Such a concept was proposed by American scholar Marvin Minsky in 1953. After 30 years of development, the laser was used as a light source to develop a confocal microscope that met Marvin Minsky's ideal.
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 an optical lens to produce an image magnification effect. Light incident by an object is magnified by at least two optical systems (objective and eyepiece). First, the objective lens produces a magnified real image, and the human eye observes the magnified real image through the eyepiece, which acts as a magnifying glass. A general optical microscope has multiple replaceable objective lenses so that the observer can change the magnification as needed. These objective lenses are generally placed on a rotatable objective lens disk, and the different eyepieces can be conveniently entered into the optical path by rotating the objective lens disk. Physicists discovered the law between magnification and resolution, and people knew that the resolution of optical microscopes has a limit. This limit of resolution limits the infinite increase of magnification. 1600 times has become the highest limit of magnification of optical microscopes, which greatly limits the application of morphology in many fields.
The resolution of optical microscopes is limited by the wavelength of light, generally not exceeding 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.
