For Fungi work you will need a 100x 0il Immersion Objective Lens
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To create a clear image at 1000 times magnification, a 100x objective lens needs to receive more light than the maximum available under normal conditions.
This is summarised as an NA, Numerical Aperture, that is more than 1. For good resolution of details the numerical aperture of a 100x magnification objective lens should be at least 1.25. |
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To achieve this extra light capacity, lens immersion oil is added between the objective lens and the cover slip on your slide and between the cover slip and slide. This is why l00x and some 60x objective lenses are known as oil immersion lenses. For more detail about how immersion Oil work click here. Using the right Immersion Oil
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By using an immersion medium with a refractive index similar to that of the glass coverslip, image degradation due to thickness variations of the cover glass are practically eliminated.
Typical immersion oils have a refractive index of 1.51 and a dispersion similar to that of glass coverslips. Light rays passing through the specimen encounter a homogeneous medium between the coverslip and immersion oil and therefore are only refracted as they leave its upper surface. This prevents image aberrations. |
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The oil used needs to be matched to the refraction index of the objective lens or you will lose the advantages of oil immersion.
Therefore, only use the oil specified by the objective manufacturer. Mixing different types of oil will produce artefacts such as crystallization. |
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