Oil immersion is the technique of using a drop of oil to wet the top of the specimen or slide cover and the front of the objective lens. This effectively immerses or bathes the light path between the lens and object viewed, allowing finer details to be seen.
Also Know, when and why should you use immersion oil? When to use an oil immersion lens Use an oil immersion lens when you have a fixed (dead - not moving) specimen that is no thicker than a few micrometers. Even then, use it only when the structures you wish to view are quite small - one or two micrometers in dimension.
Also asked, why must oil be used to obtain the best resolution with a 100x lens?
Oil is used to displace air between the lens and specimen. Bending of light rays. Occurs when light passes from a medium of one refractive index to another.
Does immersion oil increase magnification?
Inmersion oil does not increase magnification. High magnifications come with high numerical appertures (although one can have a low-magnification high-numerical apperture objective). High numerical appertures are required to capture more light and improve resolution.
