Introduction to Objective Lenses of Microscopes:

An objective lens is a lens that is closest to the object being viewed through a microscope. It is a critical component of a microscope as it forms the primary image of the specimen. The quality of the image formed by the objective lens depends on the type of lens used. There are various types of objective lenses that are used in microscopes, each with its unique properties and applications.

Achromatic Objective Lenses:

Achromatic objective lenses are designed to correct for chromatic aberrations, which is the tendency of lenses to refract different colors of light at different angles. This results in a blurred image when viewed through a microscope. Achromatic objective lenses are made of two or more lenses made of different types of glass that are cemented together. They are typically used for low-power magnification in brightfield microscopy.

Plan Objective Lenses:

Plan objective lenses are designed to correct for spherical aberrations, which is the tendency of lenses to form a curved image instead of a flat one. These lenses are made of a single piece of glass and are typically used for high-power magnification in brightfield microscopy.

Apochromatic Objective Lenses:

Apochromatic objective lenses are designed to correct for both chromatic and spherical aberrations. They are made of multiple lenses made of different types of glass that are cemented together. They are typically used for high-power magnification in fluorescence microscopy, where the specimen is labeled with fluorescent dyes.

Oil Immersion Objective Lenses:

Oil immersion objective lenses are designed to be used in conjunction with a drop of oil placed on top of the specimen. The oil increases the refractive index of the medium between the objective lens and the specimen, resulting in a higher resolution image. These lenses are typically used for high-power magnification in brightfield microscopy.

Conclusion:

Each type of objective lens has its unique properties and applications. It is important to choose the right type of objective lens depending on the type of specimen being viewed and the type of microscopy being used. With the knowledge of the different types of objective lenses, the user can make an informed decision to select the correct lens for their application, and take advantage of the benefits it offers.