Comparison between confocal microscopy and conventional optical microscopy
Microscope is the main tool for observing cells. According to different light sources, it can be divided into two categories: optical microscopes and electron microscopes. The former uses visible light (ultraviolet microscope uses ultraviolet light) as the light source, while the latter uses electron beam as the light source. Both ordinary optical microscopes and laser confocal microscopes belong to optical microscopes.
Ordinary optical microscope
A common biological microscope consists of three parts, namely: ① lighting system, including light source and condenser; ② The optical amplification system, consisting of an objective and an eyepiece, is the main body of a microscope. In order to eliminate spherical and chromatic aberration, both the eyepiece and objective are composed of complex lens groups Mechanical device, used to fix materials and facilitate observation.
The clarity of a microscope's image not only depends on its magnification, but also on its resolution. Resolution refers to the ability of a microscope (or a human eye at a distance of 25cm from the target) to distinguish objects at small intervals. The magnitude of resolution depends on the wavelength of light, the aperture index, and the refractive index of the medium. It is expressed as: R=0.61 λ/N.A.N.A.=nsin α/2, where n=the refractive index of the medium; α=aperture angle (the angle at which the specimen opens the objective lens aperture), N.A.=numerical aperture. Is the corner of the mirror always less than 180?, So the maximum value of zui for sina/2 must be less than 1.
The refractive index of glass used in the production of optical lenses is 1.65-1.78, and the closer the refractive index of the medium used is to that of glass, the better. For dry objective lenses, the medium is air, and the aperture ratio is generally 0.05-0.95; The oil lens uses cedar oil as the medium, and the aperture ratio can be close to 1.5.
The wavelength of ordinary light is 400-700nm, so the resolution value of the microscope will not be less than 0.2 μ m, and the resolution of the human eye is 0.2mm. Therefore, the maximum magnification for microscope design is usually 1000X.
