How to use the oil immersion lens of a microscope
When using an oil mirror, when selecting the observation area with a low magnification objective lens, people often underestimate the small object field of the high magnification objective lens, which may lead to focusing on an empty field of view. At the same time, the center of the objective lens is rarely extremely accurate, so the field of view of high-power objectives cannot be estimated very accurately. These pose great difficulties for the focusing of the oil mirror. In this case, very small cigarette tin foil or very thin tin foil can be sealed together with the specimen under a cover glass, making it easy to use an oil microscope to find the focusing plane that is very close to the specimen.
When using an oil immersion lens, you can directly turn it back to the low magnification objective lens for observation without wiping off the immersion oil. The immersion layer does not have a significant impact on the formation of the image when using a low magnification objective lens, and the front lens of the objective lens does not come into contact with the immersion oil. At the same time, the immersion oil on the cover glass does not increase the impact of the cover glass on the image.
The earliest immersion oil used in Olympus microscopes was cedar oil with a refractive index of 1.512-1.518. This immersion oil exhibited increased dryness and slower polymerization characteristics when exposed to air. Nowadays, many microscope manufacturers can provide a non resin synthetic immersion oil with a refractive index of 1.51-1.518 and suitable dispersion characteristics. Due to its good properties and suitability for high-quality oil immersion work, it has gradually replaced the above two types of resin immersion oil. So it is recommended to use this type of mirror oil when using oil mirrors.
Only one drop is needed for oil immersion. Excessive oil immersion is not only useless for observation, but also brings a lot of trouble to the cleaning of the oil mirror after use. At the end of the observation, even if non resin immersion oil is used, the objective lens and cover glass should be carefully cleaned. First, use dry wiping paper or cloth to wipe off the immersion oil, and then use wiping paper or cloth dipped in xylene or gasoline to wipe off the remaining immersion oil.
