Why is it necessary to wipe off the immersion oil after using oil immersion objective?

Wiping off the immersion oil after using an oil immersion objective is necessary to prevent damage to the lens and maintain optical clarity. Oil can degrade the lens coatings and attract dust or debris if left on the objective. Additionally, residue accumulation can affect the performance of subsequent observations, leading to inaccurate results. Proper cleaning ensures the longevity of the microscope and the quality of future imaging.