What is the principle of oil lens in optical microscope? Oil lens should be used to observe microorganisms
Oil lens is one of the optical microscopes. When used, the lens is immersed in oil (usually cedar oil) to observe finer structures. It is one of the microscopes commonly used in laboratories. The clarity is slightly higher than that of ordinary optical microscopes. It is used for Observe chlamydia, bacteria, cell organelles, etc. The lens of the oil lens is very small, and the light passes through the gap between the glass slide and the oil lens...
The oil lens on the microscope has a magnification of 100 times. When using it, you need to add drops of cedar oil on the glass slide to see the objects under the microscope clearly.
The reason why when using an oil lens is to add drops of cedar oil to the glass slide. This is because the magnification of the oil lens is high and the lens is very small. When light passes through media objects of different densities (glass slide → air → lens), part of the light will be refracted and lost. Less light will enter the lens barrel and the field of view will be smaller. Dark, objects cannot be seen clearly. If cedar oil (n=1.515), which is similar to the refractive index of glass (n=1.52), is dropped between the lens and the glass, the light entering the oil lens will increase, the brightness of the field of view will be enhanced, and the object image will be clear.
Microorganisms are generally small. Use an oil lens to observe them. The magnification is large and the observation is clearer!
To put it simply, the refractive index of cedar oil is less than the refractive index of air. More light passing through small cells will enter the objective lens, making it easier to observe.
Use of oil immersion objectives for optical microscopes
When using an oil immersion objective lens, generally do not use the same height adjustment. Same-height focusing is only applicable to the original objective lens of each microscope. It is an extremely advantageous and convenient condition when using low- and high-magnification objectives. However, it is subject to certain restrictions when using oil-immersion objectives. Generally speaking, when using oil-immersion objectives, When observing specimens (slides) without coverslips, it is safer to use the same height adjustment focus. However, for specimens with coverslips, use caution because the working distance of the oil immersion objective lens is very long. Short, the same height was considered during design and assembly for standard thickness coverslips.
When using an oil immersion objective, only drop cedar oil on the specimen piece. After the observation, cleaning work must be carried out in time. If not done in time, the cedar oil will stick to dust, and the dust particles may wear the lens when wiping. The cedar oil will thicken and dry out when exposed to the air for a long time, making wiping difficult. Very detrimental to the instrument. Wipe carefully and gently. First wipe the front end of the oil immersion objective lens once or twice with dry lens cleaning paper to remove most of the oil, then wipe it twice with lens cleaning paper moistened with xylene, and finally wipe it once with dry lens cleaning paper. The cedar oil on the specimen piece can be removed by the "paper pulling method" (that is, cover the cedar oil with a small piece of lens paper, then drop some xylene on the paper, and pull the paper out while it is wet. Do this three or four times in a row. Clean, generally will not damage uncoverslipped smear specimens) Wipe clean. Lens cleaning paper should also be dust-proof. Generally, before use, cut each page into 8 small pieces and store them in a clean small petri dish. It is economical and convenient to use.
