Which microscope should be used to view bacterial cells?
A microscope is an optical instrument composed of one lens or a combination of several lenses. It is a symbol of humanity entering the atomic age. An instrument used to magnify small objects and make them visible to the naked eye. Microscopes are divided into optical microscopes and electron microscopes. The optical microscope was first created in 1590 by the Dutch father and son Janssen. Modern optical microscopes can magnify objects by 1500 times, with a minimum resolution limit of 0.2 micrometers.
There are many types of optical microscopes, except for general ones, mainly including:
① A dark field microscope is a type of microscope with a dark field spotlight that allows the illuminated light beam to be directed towards the specimen from all sides instead of the central part.
② Fluorescence microscope, a microscope that uses ultraviolet light as a light source to emit fluorescence from the irradiated object. The electron microscope was first assembled by Knorr and Harroska in Berlin, Germany in 1931. This type of microscope uses a high-speed electron beam instead of a beam of light. Due to the much shorter wavelength of the electron flow compared to light waves, the magnification of the electron microscope can reach 800000 times, with a minimum resolution limit of 0.2 nanometers. The scanning electron microscope, which began to be used in 1963, allows people to see the tiny structures on the surface of objects.
Optical microscope structure
The structure of a regular optical microscope is mainly divided into three parts: mechanical part, lighting part, and optical part.
◆ Mechanical part
(1) Mirror base: It is the base of a microscope used to support the entire mirror body.
(2) Mirror column: The upright part above the mirror base, used to connect the mirror base and the mirror arm.
(3) Mirror arm: One end is connected to the mirror column and the other end is connected to the mirror tube, which is the gripping part when taking and placing a microscope.
(4) Mirror tube: Connected to the front upper part of the mirror arm, the upper end of the lens tube is equipped with an eyepiece, and the lower end is equipped with an objective lens converter.
(5) Objective lens converter (rotator): Connected to the bottom of the prism shell, it can rotate freely. There are 3-4 circular holes on the disc, which are the location for installing the objective lens. By rotating the converter, different magnifications of the objective lens can be exchanged. When a knocking sound is heard, observation can be made. At this time, the optical axis of the objective lens is precisely aligned with the center of the optical hole, and the optical path is connected.
(6) Mirror stage (loading stage): Under the mirror tube, there are two shapes: square and round, used to place glass slide labels
There is a light hole in the center of the microscope, and the microscope we use has a slide specimen pusher (slide pusher) on its mirror stage. There is a spring clip on the left side of the pusher to hold the slide specimen, and there is a pusher adjustment wheel under the mirror stage to move the slide specimen in the left, right, and front and back directions.
(7) Adjuster: It is a screw of two sizes installed on the mirror column, which moves the mirror table up and down during adjustment.
① Coarse adjuster (coarse spiral): The large spiral is called a coarse adjuster. When moving, it can make the mirror stand rise and fall quickly and significantly, so it can quickly adjust the distance between the objective lens and the specimen to present the object in the field of view. Usually, when using a low-power lens, the coarse adjuster is used first to quickly find the object.
② Fine regulator (fine spiral): The small spiral is called a fine regulator, which can slowly raise and lower the mirror table when moving. It is often used when using high-power mirrors to obtain clearer images and observe the structure of the specimen at different levels and depths.
