Use and maintenance of a biological microscope (oil mirror)
Requirements for
Familiar with the structure of biological microscopes, proficient in the use of microscopes, especially the use and maintenance of oil lenses.
Experimental content
1. The structure of a biological microscope is composed of a mechanical support and adjustment system and an optical amplification system.
(1) The mechanical components of a biological microscope are the framework of the entire microscope, which serves as the base for installing an optical amplification system. The mechanical components of a microscope include a mirror base, a mirror wedge, a mirror tube, a rotating disc, an adjuster, a stage, a thruster, a condenser, an aperture, and power adjustment.
(2) The optical amplification system components of a biological microscope include an eyepiece, objective lens, condenser, electric light source, etc.
2. Instructions and precautions for using a microscope: The microscope has a precise structure and must be used carefully. The following steps should be followed.
(1) Prepare to tightly grip the buttocks of the mirror with your right hand and hold the mirror base with your left hand. Slowly place the biological microscope on the experimental table, slightly to the left in front of your body, about 10cm away from the desk. You can place a notebook or drawing paper on the right side.
(2) Adjust the light source by minimizing the current regulator, plugging in the power, turning on the power switch, and rotating the regulator to increase the brightness from weak to strong, making it suitable for observation.
(3) Observation and positioning with a low magnification lens. The low magnification lens has a larger field of view, making it easier to detect targets and determine the location of the examination. Place the specimen on the stage, move the pusher so that the observed specimen is directly below the objective lens. Rotate the coarse adjustment screw to bring the objective lens to 5mm of the specimen. Adjust the condenser to weaken the light, observe with the objective lens, and slowly raise the stage with the coarse adjustment screw until the field of view appears *. Then, fine adjust the screw to make the field of view clear. Move it to the center of the field of view.
(4) High magnification observation, based on the positioning of low magnification observation, converts to a high magnification objective. When converting the objective, it is necessary to avoid collision between the lens and the glass slide. Then observe through the eyepiece, adjust the brightness adaptation, slowly adjust the coarse adjustment screw to raise the stage until the object image appears, then adjust the sewing adjustment screw to make the object image clear, move to the center of the field of view for observation or prepare to use a sleeve mirror for observation.
(5) Oil mirror observation, the magnification of the oil mirror is deletion times, only in this state can bacteria be observed better. The use of a polarizer requires the addition of tar, as the lens of the polarizer is very small. When light passes through the specimen and enters the air, due to different medium densities, some light cannot enter the lens due to refraction, resulting in insufficient brightness of the field of view and unclear images. Adding cedar oil (n=1.535) similar to the glass refractive index string (n=1.52) between the specimen and the microscope avoids refraction and reflection of light, enhances the brightness of the field of view, and improves resolution. The working distance of an oil immersed objective (referring to the distance between the surface of the lens in front of the objective and the object being tested) is within 0.2mm. Therefore, when using an oil immersed objective, special attention should be paid to avoid accidentally focusing and crushing the specimen, which can also damage the objective. The following steps must be followed for operation.
