objective lens
Noun: The optical element or group of elements in an optical instrument (such as a microscope or telescope) that first receives light rays from the object being observed and forms the primary image.
The term "objective lens" refers specifically to the primary light-gathering component of an optical system. It is the lens closest to the object. Its quality and specifications (like focal length and aperture) are critical for determining the instrument's magnification, resolution, and light-gathering ability.
- In a compound microscope, the objective lens is mounted on a rotating nosepiece close to the specimen slide.
- Astronomers use telescopes with a large objective lens (or mirror) to collect more light from distant stars.
- The magnification power of a microscope is often stamped on the side of each objective lens, such as 4x, 10x, or 40x.
- "To change the objective lens": This refers to the action of rotating the nosepiece on a microscope to select a lens with a different magnification power.
- For higher magnification, you should change the objective lens from 10x to 40x.
- In technical contexts, specifications like the "numerical aperture (NA) of the objective lens" are discussed, which defines its ability to gather light and resolve fine detail.
- Objective (noun): A common shortened form of "objective lens," especially in microscopy.
- Switch to the low-power objective.
- Object glass (noun): An older, less common synonym for objective lens.
- Objective system: Refers to the entire assembly of lenses that make up the objective, particularly in complex instruments.
- Object glass
- Front lens (informal, though this can sometimes refer to a specific element within a compound objective)
The "objective lens" is distinct from the eyepiece lens (or ocular), which is the lens nearest the viewer's eye and which further magnifies the primary image formed by the objective. The combination of both lenses determines the total magnification.
- the lens or system of lenses in a telescope or microscope that is nearest the object being viewed