Oil immersion

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In a light microscope, oil immersion is a technique used to increase the power of a microscope. This is achieved by immersing objective lenses and specimens in transparent oils with a high refractive index, thus increasing the objective lens's numerical openings.

Immersion is a transparent oil that has specific optical and viscosity characteristics required for use in a microscope. The special oil used has a refractive index of about 1,515. An oil immersion purpose is an objective lens specially designed to be used in this way. Many condensers also provide optimal resolution when the condenser lens is immersed in oil.

Video Oil immersion

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Lenses reconstruct light scattered by an object. In order to successfully achieve this goal, ideally, all diffraction orders must be collected. This is related to the lens opening angle and its refractive index. The microscope resolution is defined as the required minimum separation between the two objects examined in order for the microscope to distinguish them as separate objects. The minimum distance is labeled? If two objects are separated by a shorter distance from?, They will appear as single objects in a microscope.

Ukuran kekuatan penyelesaian, R.P., dari lensa diberikan oleh bukaan numeriknya, NA:

${\ displaystyle \ delta = {\ frac {\ lambda} {\ mathrm {2NA}}}}  ÂÂ$

Where? is the wavelength of light. From here it is clear that a good resolution (small?) Is connected with a high numerical opening.

Bukaan numerik lensa didefinisikan sebagai

${\ displaystyle \ mathrm {NA} = n \ sin \ alpha _ {0} \;}  ÂÂ$

where is it? ₀ half angles spanned by the objective lens seen from the sample, and n are the refractive index of the medium between the lens and the specimen (? 1 for air).

The state of the art purpose can have numerical openings of up to 0.95. Because of sin? ₀ is always less than or equal to unity (number "1"), numeric numbers can never be greater than unity for objective lenses in the air. If the space between the objective lens and the specimen is filled with oil, the numerical aperture can obtain a greater value than unity. This is because the oil has a refractive index greater than 1.

Maps Oil immersion

Purpose of oil immersion

From the above explanation it is understood that the oil between the specimen and the objective lens increases the strength of completion by a factor of 1/ n . Specific objectives designed for this purpose are known as oil immersion purposes.

The purpose of oil immersion is only used at enormous magnification requiring high completion strength. Goals with high power magnification have short focal lengths, facilitating the use of oil. The oil is applied to the specimen (conventional microscope), and the stage is raised, soaking the purpose in the oil. (In reverse microscopy, the oil is applied to the goal).

The refractive index of oil and glass in the first lens element is almost the same, which means that the refraction of light will be small upon entering the lens (oil and glass are optically very similar). The correct immersion oil for the objective lens should be used to ensure that its refractive index fits tightly. The use of oil immersion lenses with incorrect immersion oil, or without immersion oil, will have a spherical aberration. The strength of this effect depends on the size of the refractive index mismatch.

Oil immersion generally can only be used on specimens that are rigidly mounted if the surface tension of the oil can move the cover glass and move the sample underneath. This can also happen on an inverted microscope because the cover glass is under the slide.

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Immersion oil

Prior to the development of synthetic immersion oils in the 1940s, cedar tree oil was widely used. Cedar oil has a refractive index of about 1.516. The numerical opening of the cedar tree oil goal is generally about 1.3. However, Cedar oil has several disadvantages: it absorbs blue and ultraviolet light, yellow with age, has enough acidity to potentially damage its purpose by repeated use (by attacking the cement used to join the lens), and diluting it with the solvent altering its viscosity (and refractive index and dispersion). Cedar oil should be removed from the destination as soon as it is used before it can harden, as hardened cedar oil can damage the lens. In modern microscopy, synthetic immersion oil is more commonly used, because they eliminate most of these problems. The value of NA 1.6 can be achieved with different oils. Unlike synthetic natural oils that do not harden on the lens and can usually be left on purpose for months at a time.

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See also

• Purpose of water immersion
• The index matching material
• Solid immersion lens

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References

• Practical Microscope by L.C. Martin and B.K. Johnson, Glasgow (1966).
• Light Microscope by J.K. Solberg, Tapir Trykk (2000).

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External links

• "Purpose Microscope: Immersion Media" by Mortimer Abramowitz and Michael W. Davidson, Olympus Microscopy Resource Center (website), 2002.
• "Immersion Oil Microscopy" by David B. Fankhauser, Biology at the University of Cincinnati, Clermont College (website), December 30, 2004.
• "History of Oil Immersion Lenses" by Jim Solliday, Southwest Engineering, Communication and Computing Museum (website), 2007.
• "Immersion Oil and the Microscope" by John J. Cargille, New York Microscopical Society Yearbook , 1964 (revised, 1985). (Archived at Cargille Labs (website).)

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