Biological microscope is a kind of precision optical instrument commonly used in biology teaching experiment, which is composed of mechanical system and optical system.

　　The mechanical system includes: the transmission part of the lens barrel, the rotation part of the objective lens, the stage, the conversion part of the film clamp and the shutter, the rotation part of the frame and the base, etc.

　　Optical system includes: eyepiece, objective lens, condenser and mirror, etc.

　　 One, maintenance and maintenance

　　 1. Overall maintenance: The biological microscope should be placed in a dry, cool, dust-free, and non-corrosive place. After use, wipe it clean immediately, cover it with a dust-proof vent or put it in a box.

　　 2. Maintenance of the mechanical system: After use, wipe it with a clean fine cloth, and regularly apply some neutral grease to the sliding part. If there is serious pollution, you can wash it with gasoline and then dry it. But do not use alcohol or ether to clean, because these reagents will corrode the machinery and paint, causing damage.

　　 3. Maintenance of the optical system: After use, gently wipe the eyepiece and objective lens with a clean and soft silk cloth. When there are stains that cannot be wiped off, use long-fiber absorbent cotton or a clean fine cotton cloth dipped in less dimethyl benzene or lens cleaning solution (3 parts alcohol:1 part ether) to wipe. Then wipe dry with a clean soft silk cloth or blow dry with a hair dryer. It should be noted that the cleaning liquid must not penetrate into the objective lens, otherwise it will damage the objective lens. The condenser (only available for XSP-12A and 16A) and the mirror after use, just wipe them clean.

　　 2. Common troubleshooting

　　 1. The self-slip of the lens barrel: This is one of the frequent failures of biological microscopes. The solution to the sleeve structure of the microscope can be divided into two steps.

　　The first step: Hold the two coarse adjustment handwheels with both hands, and tighten them relatively firmly. See if the problem can be solved. If the problem cannot be solved, use a special double-post wrench to unscrew a coarse adjustment handwheel and add a friction plate. After the handwheel is tightened, if the rotation is difficult, add a friction plate. It's too thick, you can replace it with a thin one. Take the handwheel to rotate effortlessly, and the lens barrel can move up and down easily without sliding down by itself. The friction sheet can be punched with a puncher using waste photographic film and a soft plastic sheet less than 1 mm thick.

　　 Step 2: Check the meshing state of the gear on the coarse adjustment handwheel shaft and the rack on the lens barrel. The up and down movement of the lens barrel is completed by a gear driven rack. The best meshing state of gear and rack is theoretically that the index line of the rack is tangent to the index circle of the gear. In this state, the gear rotates easily and the wear on the rack is minimal. Now there is a wrong way to add a shim behind the rack to make the rack press the gear tightly to prevent the lens barrel from sliding down. At this time, the index line of the rack intersects the index circle of the gear, and the tooth tips of the gear and the rack are tightly against each other's tooth root. When the gears rotate, severe grinding occurs between each other. Because the rack is made of copper, the gear is made of steel. Therefore, the mutual grinding will damage the teeth on the rack, and there will be a lot of copper chips on the gear and rack. In the end, the rack will be severely worn and unusable. Therefore, do not use a booster rack to prevent the lens barrel from sliding down. Solving the problem of the lens barrel sliding down by itself can only be achieved by increasing the friction between the coarse adjustment handwheel and the eccentric shaft sleeve.

　　 But there is one exception, that is, the index line of the rack is separated from the index circle of the gear. At this time, when the coarse adjustment handwheel is turned, idling slip will also occur, which will affect the up and down movement of the lens barrel. If this is done by adjusting the eccentric sleeve of the coarse adjustment handwheel, the meshing distance between the gear and the rack cannot be adjusted. It can only be solved by adding a suitable sheet behind the rack. The standard for adjusting the meshing distance between the gear and the rack by adding spacers is: turning the coarse adjustment handwheel does not take much effort, but it does not run idly. After adjusting the distance, add some neutral grease between the gear and the rack. Just move the lens barrel up and down a few times. Finally, the two compression screws on the eccentric shaft sleeve must be tightened. Otherwise, when the coarse adjustment handwheel is turned, the eccentric shaft sleeve may follow the rotation, and the rack will be blocked, making the mirror holder unable to move up and down. At this time, if the force of turning the coarse adjustment handwheel is too large, the rack and the eccentric shaft sleeve may be damaged. After tightening the compression screw, if it is found that the eccentric sleeve is still rotating. This is because the screw hole thread of the compression screw is not changed properly. Because the manufacturer uses a machine to change the thread, there are often one or two threads that are not changed in place. At this time, even if the compression screw is not screwed in place, the eccentric sleeve cannot be compressed.

　　 After completing the above steps one by one, the problem of the lens barrel sliding down by itself is basically completely solved.