objectives (original) (raw)

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

Categories: general optics, vision, displays and imaging

• lenses
  • achromatic lenses
  • aspheric aspheric
  • ball lenses
  • condensers
  • cylindrical lenses
  • diffractive lenses
  • f–theta lenses
  • fiber lenses
  • field lenses
  • Fresnel lenses
  • gradient-index lenses
  • Kerr lens
  • loupes
  • magnifying glasses
  • microlens arrays
  • microlenses
  • objectives
    * photographic objectives
    * microscope objectives
  • ocular lenses
  • rod lenses
  • scanning lenses
  • telecentric lenses
  • zoom lenses
  • (more topics)

Related: microscope objectiveszoom lensesphoto camerastelescopes

Opposite term: ocular lenses

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DOI: 10.61835/8rs Cite the article: BibTex BibLaTex plain textHTML Link to this page! LinkedIn

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📦 For purchasing objective lenses, use the RP Photonics Buyer's Guide — an expert-curated directory for finding all relevant suppliers, which also offers advanced purchasing assistance.

Contents

What are Objectives?

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

• A microscope objective is the component of a microscope which is placed next to the object. Its numerical aperture is the key factor which limits the achievable image resolution of the microscope. It also substantially contributes to the magnification of the instrument, which is further increased with an eyepiece. Similar objectives are also used for optical profilometers.

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

• A photographic objective is the part where light enters a photo camera. There are different versions of such camera objectives, e.g. zoom objectives with a variable magnification, telephoto objectives for taking images from rather distant objects, macro objectives for large magnification of small close objects and wide-angle “fish eye” objectives.
• Similarly, a telescope objective collects input light for a telescope. Such devices are often optimized for viewing distant images with large magnification. The entrance diameter is important not only concerning the light gathering power, but also ultimately limiting the image resolution.
• Infrared viewers have objectives which are optimized for receiving infrared light.
• There are specialized interferometry objectives, which contain a beam splitter and a reference mirror. They are used in certain optical profilometers, for example.

In other cases, objectives are optical components for sending light to an object. For example, there are projection 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 high optical performance, with minimal image aberrations, can be achieved only with a careful combination of lenses. In the 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.

Objectives with Variable Focal Length

Many objectives, e.g. for photo and video cameras, offer a variable focal length. In the simplest case, they are called varifocal, but often they also have parfocal performance, meaning that they preserve focus when zooming, and in that case they are called zoom objectives or zoom lenses.

Frequently Asked Questions

What is an optical objective?

An optical objective is an optical element or system used either to collect light from an object for imaging or to send light to an object. Common examples include microscope objectives, photographic objectives, and telescope objectives.

Why do most objectives consist of multiple lenses?

Most objectives are multi-element systems because high optical performance, particularly the correction of various image aberrations, can only be achieved with a careful combination of multiple lenses, often arranged in groups.

What is a zoom objective?

A zoom objective is an objective with a variable focal length. It is also 'parfocal', meaning that it is designed to preserve the focus on an object when its magnification is changed by zooming.

Suppliers

Sponsored content: The RP Photonics Buyer's Guide contains 66 suppliers for objective lenses. Among them:

⚙ hardware

Avantier is a leading manufacturer of high-performance microscope objective lenses designed for research, industrial, medical, and forensic applications. We offer both in-stock lenses for immediate use and custom-engineered objectives optimized for specific spectral ranges including NIR, NUV, and UV. Our portfolio includes achromatic, plan achromatic, semi-apochromatic and fully apochromatic versions. Avantier objective lenses are compatible with all major microscope systems. Custom versions can also be made.

What truly sets Avantier apart is our ability to deliver high numerical aperture (NA) and long working distance objective lenses — a combination rarely achieved by other manufacturers. These lenses enable superior resolution, light-gathering efficiency, and imaging flexibility, even in challenging setups or specialized environments.

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