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Definition: optical elements for collecting light from inspected objects, or for sending light to objects

German: Objektive

Categories: general optics, vision, displays and imaging

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Objectives are frequently understood as optical elements for collecting light from inspected objects:

fish-eye objective
Figure 1: A fish-eye objective. Source: Excelitas Technologies

In other cases, objectives are optical components for sending light to an object. For example, there are protection objectives, used e.g. in laser projection displays, and focusing objectives. It also happens, for example, that a microscope objective is used for focusing a laser beam into an optical fiber, i.e., as a focusing objective. Such objectives are often optimized for improved power handling capability.

Single-lens or Multi-lens Systems

A simple objective may essentially consist of a single lens. However, most objectives are multi-element lens systems, containing some number of lenses and often one or more optical apertures, because of the optical performance in terms of various types of image aberrations can be achieved only with a careful combination of lenses. In case of telescopes, objectives are often based on curved mirrors instead of lenses.

Single lenses, including cemented doublets and triplets, in an objective are called elements of the objective. Certain subsets of elements are often called groups.

The optical design of objectives is usually a sophisticated task, for which specialized optical design software is used. It involves trade-offs between different qualities, which should be optimized according to the specific application.

See also: microscope objectives, lenses, photo cameras, telescopes
and other articles in the categories general optics, vision, displays and imaging

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