Introducing the mechanical components and how optical microscopes work
The mechanical device of the microscope is an important part of the microscope. Its function is to fix and adjust the optical lens, fix and move the specimen, etc. It mainly consists of a lens base, a lens arm, a stage, a lens barrel, an objective lens converter, and a focusing device.
(1) Mirror base and mirror arm
1. The mirror base is used to support the entire microscope and is equipped with a reflector and some lighting sources.
2. The mirror arm is used to support the lens barrel and the stage. There are two types: fixed and tiltable.
(2) Stage (also known as workbench and mirror stage)
The stage is used to place glass slides. There are two shapes: round and square. The square area is 120mm×110mm. There is a light hole in the center, and there are small holes on the left and right sides behind the light hole for installing tablet clamps. There are two types: fixed and mobile. Some stages are equipped with vernier rulers on the vertical and horizontal coordinates. The general reading is 0.1mm. The vernier ruler can be used to measure the size of the specimen and can also be used to mark the part to be inspected.
(3) Lens tube
The eyepiece is placed on the upper end of the lens barrel, and the objective lens converter is connected on the lower end. There are two types: fixed and adjustable. The length of the mechanical tube (the distance from the upper edge of the eyepiece tube to the lower end of the screw port of the objective lens converter is called the tube length or the mechanical tube length) cannot be changed and is called a fixed tube, and the one that can be changed is called an adjustable tube. Most new microscopes use Fixed lens tube. Most domestic microscopes also use fixed lens tubes. The mechanical tube length of domestic microscopes is usually 160mm.
There are two types of lens tubes for installing eyepieces: single tube and binocular. Single tubes can be divided into two types: upright and tilted, while double tubes are both tilted. Among them, binocular microscope allows two eyes to observe at the same time to reduce eye fatigue. The distance between the binoculars can be adjusted, and one of the eyepieces has a diopter adjustment (ie, vision adjustment) device to facilitate use by observers with different vision in the two eyes.
(4) Objective converter
The objective converter is fixed at the lower end of the lens barrel and has 3-4 objective lens screw ports. The objective lenses should be arranged in order of magnification. When rotating the nosepiece, hold the rotating disk with your fingers and do not push the objective lens with your fingers. This may cause the optical axis to skew over time, which may degrade the image quality.
(5) Focusing device
The microscope is equipped with a coarse quasi-focus screw and a fine quasi-focus screw. In some microscopes, the coarse focus spiral and the microscope are installed on the same axis. The large spiral is the coarse focus spiral and the small spiral is the fine focus spiral. Some microscopes are installed separately. The larger pair of spirals located at the upper end of the mirror arm is the coarse focus spiral. The quasi-focus screw rotates once and the lens barrel rises or falls by 10mm. The smaller pair of spirals located below the coarse focus spiral are the fine focus spirals. When they rotate once, the lens barrel lift value is 0.1mm, and the focusing range of the fine focus spiral is not less than 1.8mm.
