The use of oil mirrors in optical microscopes
Identification of oil lens:
The magnification of each objective can be identified by its appearance. The longer the lens length, the smaller the lens diameter, and the greater the magnification; On the contrary, the magnification is small. The length of the oil lens is greater than that of low and high magnification lenses, and the lower edge of the lens is generally engraved with a circle of black or white lines, and is also engraved with 100 ×、 Words such as 1.25 or oil.
Usage of oil mirror:
1. When using a microscope oil mirror, the microscope must be upright on the table, and the mirror arm must not be bent to tilt the stage, in order to avoid the overflow of tar, affecting observation, and polluting the table.
2. Aiming:
When using natural light as the light source, it is advisable to use a flat reflector; If using artificial lighting, use a concave mirror. Firstly, open the aperture and rotate the reflector to concentrate the light on the collector. You can move the concentrator up and down and scale the aperture as needed to achieve the best brightness.
When observing the object with a low-power or high-power microscope or examining an unstained specimen with an oil microscope, it is necessary to lower the light collector and appropriately reduce the aperture to weaken the luminosity; When using an oil microscope to examine stained specimens, the luminosity should be strong. The brightness switch of the microscope should be turned to * bright, the aperture should be fully opened, and the light collector should rise to level with the stage.
3. Zoom length:
A. Place the specimen slide on the stage, fix it with a specimen pusher, and move the part to be examined under the objective lens. First, use a low-power microscope to locate the position of the specimen, then raise the lens tube, apply one drop of lens oil to the area to be tested, and then change the oil lens for observation.
B. Rotate the coarse adjuster to slowly raise the stage (or gradually lower the lens tube) until the oil lens is immersed in the oil. At this point, the eyes should be observed from the side to avoid crushing the specimen and damaging the lens.
C. Then move your eyes to the eyepiece, observe from the eyepiece while slowly rotating the coarse adjuster (lowering the stage or raising the lens tube) in the opposite direction. When a blurry object appears, switch to a fine adjuster and rotate until the object is clear
D. After observation, the lens tube should be raised first, and the oil lens should be twisted to one side before removing the specimen. After using the oil lens, the oil on the lens should be immediately wiped off with lens wiping paper. If the lens oil is sticky and dry on the lens, a small amount of xylene can be dipped in the lens wiping paper to wipe the lens, and then the remaining xylene can be wiped off with dry lens paper to prevent xylene from infiltrating and dissolving the gum used to fix the lens, causing lens displacement or detachment.
The principle of using oil mirrors:
The lens of the oil lens is very small. When light passes through the air between the glass slide and the oil lens, refraction or total reflection occurs due to different media densities, reducing the amount of light entering the lens and blurring the image. If cedar oil (n=1.515) with a refractive index similar to that of the glass (n=1.52) is added between the oil mirror and the glass slide, it will increase the amount of light entering the lens, enhance the brightness of the field of view, and make the object image bright and clear.
