Objective lens

Objective lens

The objective lens or object glass is the primary lens or assembly of lenses in a telescope or microscope that gathers light from the object being observed and focuses the light rays to produce a real image. Objective lenses are also used in microscopes, telescopes, and cameras to gather light and focus it to create an image.

Function

The objective lens of a microscope is the one at the bottom near the sample. At its simplest, it is a very high-powered magnifying glass, with very short focal length. This is brought very close to the specimen being examined so that the light from the specimen comes to a focus inside the microscope tube. The objective itself is usually a cylinder containing one or more lenses that are typically made of glass; its function is to collect light from the sample.

Types of Objective Lenses

There are several types of objective lenses, including:

• Achromatic lens: These lenses are designed to limit the effects of chromatic and spherical aberration. Achromatic lenses are corrected to bring two wavelengths into focus in the same plane.

• Apochromatic lens: These lenses are designed to bring three wavelengths into focus in the same plane.

• Plan lens: These lenses are designed to focus light onto a flat plane, as opposed to a curved plane.

See also

• Eyepiece
• Optical microscope
• Telescope

References

Objective lens Resources
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