Glycerin is needed to be used in the 100 times objective of microscope to observe the specimen clearly. Some problems in the use of oil lens of microscope must be paid attention to. Because of the short free working distance and small field depth of this kind of objective, the focusing of object image becomes a very difficult problem. If the object image is not seen, the resistance of the microscope can continue to advance with fine adjustment, but this may cause serious consequences. The front lens of the objective may be damaged or blurred due to impact, or the cover glass may be broken.
Now a solution to this problem is the widely used safety object with elastic protection device, which has a certain elastic stretching distance. This kind of protective device has been widely used in oil lens, and it is also used in some brands of related objective lens. When using the oil lens, how can we better protect the oil lens
In the use of oil lens, when the low power coherent objective is used to select the observation area, people often underestimate the small object field of the high power objective, so that they may focus on an empty field of view. At the same time, the center of objective lens is rarely very accurate, so the field of view of high power objective lens can not be estimated accurately. These bring great difficulties to the focusing of oil lens. In this case, a very small piece of cigarette tin paper or a very thin piece of tin foil can be sealed under the cover glass together with the specimen, so that the focus plane close to the specimen can be easily found by using the oil microscope.
When the oil lens is used, it can be directly turned back to the low power objective lens for observation without wiping off the immersion oil. The oil immersion layer has no great influence on the image formation when using the low power objective lens, and the front lens of the objective lens will not contact the oil immersion, and the oil immersion on the cover glass will not increase the influence of the cover glass on the image.
The first immersion oil used in Olympus microscope is Cunninghamia lanceolata oil with refractive index of 1.512-1.518. When exposed to air, this immersion oil has the characteristics of higher wither and slower polymerization. Now many microscope manufacturers can provide a kind of non resin synthetic immersion oil with refractive index of 1.515-1.518 and suitable dispersion characteristics. Because of its good characteristics and suitability for high-quality oil immersion work, it has gradually replaced the above two resin based immersion oils. Therefore, it is recommended to use this kind of mirror oil when using oil mirrors.
Only one drop of oil is needed. Too much oil immersion is not only useless for observation, but also brings a lot of trouble to the cleaning of oil mirror after use. At the end of the observation, even if the non resin immersion oil is used, the objective lens and cover glass slide should be cleaned carefully. First, wipe off the immersion oil with dry lens paper or dry cloth, and then wipe off the residual immersion oil with lens paper or cloth dipped in xylene or gasoline.