homogeneous.īut oil is not the only immersion medium. It is called “homogeneous” because the refractive index of the substage condenser lens, oil, slide, mounting medium, coverglass, oil, and front lens of the objective are all the same value, ~1.515, i.e. Some older objectives indicate their requirement for oil immersion through the engraved letters “ HI” which stands for “ homogeneous immersion”, as indicated on the far-right objective in Figure 32-1. The third objective, a Zeiss oil immersion objective, also specifies “Oel” (= oil) as the immersion medium. It is not only 100X objectives that are made to be used immersed, as the above 25X example shows objective magnification may be anything from 10X….on up. This 25X objective is also specifically designed to work with ultraviolet light for UV fluorescence (“Fluoresz”) procedures. The second-from-left Leitz objective specifies “Oel” (German oel = oil) as the immersion medium the front lens of this objective also needs to be dipped in a drop of oil placed on top of the specimen coverglass. Note that the Olympus objective to the far left in Figure 32-1 specifies “Oil”, right after the magnification (100X) and the numerical aperture (1.30) the “ P” means that the objective is suitable for use on a polarizing microscope, where the objectives are required to be strain-free. That refractive index is essentially identical to the refractive index of the glass that makes up the objective’s front lens. For example, Figure 32-1 shows four objectives which require the use of oil to work properly-not any oil, but one made specifically for use with oil immersion objectives this oil will have a refractive index of about n D 25☌=1.515. It will be engraved right on the objective. How do I know if I have an immersion objective? An immersion objective is one that requires the use of some specified liquid between the objective front lens and the specimen slide, and, usually, between the top of the substage condenser lens and the bottom of the slide that is, the objective is “immersed” in the specified immersion medium so as to exclude and replace all air from between the objective front lens and coverglass on the specimen, and from between the substage condenser top lens and the bottom of the slide. The refractive index of air is n D 25☌=1.00.
The vast majority of microscope objectives are used “dry” that is, there is no liquid of any kind between the front lens of the objective and the top of the specimen coverglass air is the (dry) medium. Procedure/Discussion What is an immersion objective? Immersion oil de-ionzed distilled water glycerin xylene (or other cleaning solvent) lens paper microscope slide specimens. Oil immersion objective and/or water immersion objective and/or glycerin immersion objective. To learn how and why to use immersion objectives Level We hope you will find these online microscope activities valuable. You may complete these 36 activities in consecutive order as presented in the original classroom workshop, or skip around to those you find interesting or helpful. The activities were originally designed for a Boreal/Motic monocular microscope, but the Discussion and Task sections are transferable to most microscopes. We thought that these basic microscope techniques would be of interest not only for science teachers, but also for homeschoolers and amateur microscopists. In the past, Hooke College of Applied Sciences offered a microscopy workshop for middle school and high school science teachers.
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