Structure and use of the microscope
1. Mechanical parts:
The mechanical part of the microscope includes the mirror base, mirror barrel, objective converter, carrier stage, pusher, coarse adjustment handwheel, fine adjustment handwheel and other parts.
(1) Mirror base: the mirror base is the basic support of the microscope, which consists of two parts: the base and the mirror arm. It consists of two parts: the base and the mirror arm. It is connected with the carrier table and the mirror tube, which is used to install the foundation of the optical magnification system components. The base and mirror arm play a role in stabilising and supporting the whole microscope.
(2) lens barrel: the lens barrel connected to the eyepiece, connected to the lower converter, forming a darkroom between the eyepiece and the objective lens (mounted under the converter). The distance from the rear edge of the objective lens to the end of the barrel is called the mechanical barrel length. Because the magnification of the objective lens is for a certain barrel length. A change in the length of the barrel not only changes the magnification with it, but also affects the quality of the image. Therefore, when using a microscope, you can not arbitrarily change the length of the lens barrel. Internationally, the standard length of the microscope tube is 160mm, and this number is usually marked on the housing of the objective lens. There are two types of barrels: monocular and binocular; monocular barrels are divided into upright and tilted barrels, while binocular barrels are tilted barrels.
(3) Objective converter: Objective converter can be installed on three to four receiving lenses, generally three receiving lenses (low magnification, high magnification and oil lenses). Turn the converter, can be required to one of the receiving lens and lens barrel alignment (note that the rotation of the conversion for the selection of lenses, can not grasp the lens of the objective lens to turn), with the eyepiece to constitute a magnification system.
(4) carrier stage: carrier stage in the centre of a hole, for the light channel. On the stage is equipped with a spring specimen clip and pusher, its role is to fix and move the position of the specimen, so that the object is located in the centre of the field of vision.
(5) pusher: is to move the specimen mechanical device, it is by a horizontal and vertical two propulsion tooth axis of the metal frame, good microscope in the longitudinal and transversal frame pole engraved with a graduated scale, constitute a very precise plane coordinate system. If we need to repeat a part of the observation, you can note down the value of the vertical and horizontal scale, and then move to the same value can be found.
(6) coarse adjusting handwheel (coarse spiral): coarse adjusting handwheel is a rapid movement to adjust the distance between the objective lens and specimen.
(7) micro-adjustment handwheel (fine spiral): with the coarse adjustment handwheel can only roughly adjust the focus, to get the clearest object, you need to use the macro spiral to do fine-tuning.
2. Illumination part
Installed in the lower part of the stage, composed of a reflector (or light source), a concentrator and an aperture.
1) Reflector: Early optical microscopes used natural light to examine objects and were equipped with a reflector on the mirror base. Reflector is composed of a plane and another concave mirror, can be projected on it to reflect the light to the concentrator lens used to illuminate the specimen. Concave mirrors are also used to converge light. Modern optical microscopes generally use electric light source, no reflector, and can adjust the intensity of light.
(2) concentrator: concentrator in the carrier table below, it is by a set of concentrating lens and lift the spiral composition. Concentrator installed in the carrier under the table, its role is to reflect the light source by the reflector to focus the light on the sample to get the strongest illumination, so that the object to get a bright and clear effect. The height of the concentrator can be adjusted so that the focus falls on the examined object to get the maximum brightness. Generally the focus of the concentrator in its upper 1.25mm, and its rising limit for the carrier plate plane below 0.1mm. therefore, the requirements of the use of the slide thickness should be between 0.8 ~ 1.2mm, otherwise the sample is not examined in the focus, affecting the effect of microscopy.
(3) aperture: the front of the condenser front lens group is also equipped with iridescent aperture, which can be opened and narrowed to control the amount of light passing through, thus affecting the imaging resolution and contrast, if the iridescent aperture is open too large, more than the numerical aperture of the objective lens, it produces a light spot; if the contraction of the iridescent aperture is too small, the resolution decreases, and the contrast increases. Therefore, in the observation, through the iris aperture adjustment and then the field of view diaphragm (microscope with field of view diaphragm) open to the field of view of the periphery of the outer tangent, so that the field of view outside the light does not get light illumination, so as to avoid the interference of scattered light.
