Microscopy:The Instruments 。Refractive index is Unrefracted Oil immersion light objective lens the light-bending ability of a medium. Without immersion oil ·The light may bend in Immersion oil air so much that it misses the small Glass slide high-magnification lens. Condenser lenses 。Immersion oil is used Condenser to keep light from bending. Iris diaphragm Light source Figure 3.3• Refractive index is the light-bending ability of a medium. • The light may bend in air so much that it misses the small high-magnification lens. • Immersion oil is used to keep light from bending. Microscopy: The Instruments Figure 3.3