Objective lens

Definition

The objective lens is the primary lens in a microscope that gathers light from the specimen and focuses it to create an image. It is critical for determining the magnification and resolution of the microscope.

5 Must Know Facts For Your Next Test

1. Objective lenses come in different magnifications, commonly 4x, 10x, 40x, and 100x.
2. They are positioned closest to the specimen and are essential for image clarity.
3. High-magnification objective lenses often require immersion oil to enhance resolution.
4. The numerical aperture (NA) of an objective lens determines its ability to gather light and resolve fine specimen detail.
5. Objective lenses are part of a compound microscope's optical system, working with eyepiece lenses to achieve total magnification.

Review Questions

• What role does the objective lens play in a microscope?
• How does numerical aperture (NA) affect the performance of an objective lens?
• Why might immersion oil be used with high-magnification objective lenses?

Related terms

Eyepiece Lens: The lens you look through in a microscope which further magnifies the image produced by the objective lens.

Numerical Aperture (NA): A dimensionless number that characterizes the range of angles over which the system can accept or emit light.

Compound Microscope: A microscope that uses multiple lenses (objective and eyepiece) to achieve higher levels of magnification.