Immersion oil is used to increase the resolution of a microscope by immersing the objective in a transparent oil of high refractive index.
Nikon manufactures two types of Immersion Oil for microscopy - Type N and Type F. These oils are tested using Nikon objectives and therefore the performance cannot be guaranteed against lenses manufactured by other companies. The refractive indices of other manufactured oils may differ which will impair the results gained from using these with Nikon objectives. It is also important to note that oils should not be mixed, as this will impair performance.
Type N is a general purpose oil used for imaging applications requiring oil immersion, such as brightfield, darkfield, DIC and phase contrast. It is available in 8ml, 50ml and 480ml sizes, all supplied with a pipette for dispensing. Type F is considered to be the superior grade oil specifically designed for the ever growing need to improve signal to noise ratios in fluorescence microscopy. This oil is also recommended for use with Nikon’s proprietary Perfect Focus System (PFS) for long-term time-lapse experiments. The improved quality is due to the type of raw materials used in the oil, which relates to a subsequent reduction of autofluorescence caused by minerals in the oil. There is one size available at 30ml, which is supplied with a plastic pipette for dispensing.