Öljyimmersiossa

Öljyimmersiossa, meaning "oil immersion" in Finnish, refers to a technique used in microscopy that significantly enhances the resolution and clarity of an image. This method involves placing a drop of immersion oil between the objective lens and the specimen slide. The primary purpose of the oil is to increase the refractive index between the two surfaces, thereby reducing light scattering.

When light passes from the glass slide, through the air, and into the objective lens, some of the light rays refract, or bend, away from the lens. This bending causes a loss of detail and reduces the overall resolution of the microscope. Immersion oil has a refractive index very close to that of glass, which is typically around 1.515. By filling the gap with this oil, the light rays are guided more directly into the objective lens with less deviation.

This technique is particularly crucial when using high-magnification objective lenses, such as those with 40x or 100x magnification, as the effect of light scattering becomes more pronounced at these levels. Oil immersion objectives are specifically designed to be used with immersion oil and often have "Oil" or "HI" (High Immersion) marked on them. To perform oil immersion, a small drop of the specialized, non-drying immersion oil is placed on the coverslip of the specimen. The objective lens is then carefully lowered into the oil until it makes contact. After observation, the oil must be meticulously cleaned from both the objective lens and the slide to prevent damage and residue buildup.