WordNet

belonging to immediate experience of actual things or events; "objective benefits"; "an objective example"; "there is no objective evidence of anything of the kind"
the lens or system of lenses in a telescope or microscope that is nearest the object being viewed (同)objective_lens, object lens, object_glass
serving as or indicating the object of a verb or of certain prepositions and used for certain other purposes; "objective case"; "accusative endings" (同)accusative
emphasizing or expressing things as perceived without distortion of personal feelings, insertion of fictional matter, or interpretation; "objective art" (同)documentary
undistorted by emotion or personal bias; based on observable phenomena; "an objective appraisal"; "objective evidence" (同)nonsubjective
electronic equipment that uses a magnetic or electric field in order to focus a beam of electrons (同)electron lens
a transparent optical device used to converge or diverge transmitted light and to form images (同)lense, lens system
biconvex transparent body situated behind the iris in the eye; its role (along with the cornea) is to focuses light on the retina (同)crystalline_lens, lens of the eye
(metaphor) a channel through which something can be seen or understood; "the writer is the lens through which history can be seen"
genus of small erect or climbing herbs with pinnate leaves and small inconspicuous white flowers and small flattened pods: lentils (同)genus Lens

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(心の中だけでなく)実際に存在する / 客観的な / (文法て)目的格の / 目標,目的 / (文法で)目的格 / 対物レンズ
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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/01/21 18:49:02」(JST)

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Several objective lenses on a microscope.

In optical engineering, the objective is the optical element that gathers light from the object being observed and focuses the light rays to produce a real image. Objectives can be single lenses or mirrors, or combinations of several optical elements. They are used in microscopes, telescopes, cameras, slide projectors, CD players and many other optical instruments. Objectives are also called object lenses, object glasses, or objective glasses.

Types

Microscope

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.

A typical microscope has three or four objective lenses with different focal lengths screwed into a circular nose piece which may be rotated to select the required lens. These lenses are often color coded for easier use. The least powerful lens is called the scanning objective lens. This lens has the ability to magnify an object to four times its normal size. The slightly more powerful lens is referred to as the small objective lens and can typically magnify an object to ten times its size. The most powerful lens out of the three is referred to as the large objective lens and magnifies an object to 40–100 times its original size. Some microscopes also include an oil-immersion objective lens, which can magnify the specimen to over one hundred times its original size.

Microscope objectives are characterized by two parameters: magnification and numerical aperture. The former typically ranges from 4× to 100×, while the latter ranges from 0.10 to 1.25, corresponding to focal lengths of about 40 to 2 mm, respectively. For high magnification applications, an oil-immersion objective or water-immersion objective has to be used. The objective is specially designed and refractive index matching oil or water must fill the air gap between the front element and the object to allow the numerical aperture to exceed 1, and hence give greater resolution at high magnification. Numerical apertures as high as 1.6 can be achieved with oil immersion.^[1]

Photography and imaging

Camera lenses (usually referred to as "photographic objectives" instead of simply "objectives"^[2]) need to cover a large focal plane so are made up of a number of optical lens elements to correct optical aberrations. Image projectors (such as video, movie, and slide projectors) use objective lenses that simply reverse the function of a camera lens,^[3] with lenses designed to cover a large image plane and project it at a distance onto another surface.

Telescope

In a telescope the objective is the lens at the front end of a refractor or the image-forming primary mirror of a reflecting or catadioptric telescope. A telescope's light-gathering power and angular resolution are both directly related to the diameter (or "aperture") of its objective lens or mirror. The larger the objective, the dimmer the object it can view and the more detail it can resolve.

A photographic objective, focal length 50 mm, aperture 1:1.4
Diastar projection objective from a 35 mm movie projector, (focal length 400 mm).
Two Leica oil immersion microscope objective lenses; left 100×, right 40×.
The segmented hexagonal objective mirror of the Keck 2 Telescope

References

^ Kenneth, Spring; Keller, H. Ernst; Davidson, Michael W. "Microscope objectives". Olympus Microscopy Resource Center. Retrieved 29 Oct 2008.
^ The Focal encyclopedia of photography by Leslie Stroebel, Richard D. Zakia, 1993 edition, page 515
^ Light fantastic: the art and design of stage lighting, Max Keller, Johannes Weiss - page 71

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English Journal

Perceived discontinuities and continuities in transdisciplinary scientific working groups.

Crowston K1, Specht A2, Hoover C3, Chudoba KM4, Watson-Manheim MB5.
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Separation of three-dimensional scattering effects in tilt-series Fourier ptychography.

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Generation of vectorial optical fields with slot-antenna-based metasurface.

Wang S, Abeysinghe DC, Zhan Q.
Optics letters.Opt Lett.2015 Oct 15;40(20):4711-4. doi: 10.1364/OL.40.004711.
A transmission-type metasurface composed of carefully designed rectangular slot antennas for the generation of vectorial optical fields is proposed and demonstrated. Acting as local linear polarizers, these slot antennas enable the spatial modulation of optical fields in amplitude, phase, and polari
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Japanese Journal

Resolution Limits of Nanoimprinted Patterns by Fluorescence Microscopy

Kubo Shoichi,Tomioka Tatsuya,Nakagawa Masaru
Jpn J Appl Phys 52(6), 06GJ01-06GJ01-6, 2013-06-25
… The space width of 100 nm was demonstrated to be sufficient to resolve 300-nm-wide lines in the detection wavelength range of 575--625 nm using an objective lens of \mathrm{NA}= 1.40. …
NAID 40019677902

Electron Optical Properties of Microcolumn with Field Emitter

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Jpn J Appl Phys 52(3), 036603-036603-5, 2013-03-25
… The microcolumn consists of an objective lens and an electron gun, which is composed of a microscale field emitter and a condenser lens. … An acceleration lens was used as the objective lens. …
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Evaluation of methyl methacrylate monomer cytotoxicity in dental lab technicians using buccal micronucleus cytome assay

AZHAR Dawasaz Ali,SYED Sadatullah,LUQMAN Master,ALI Assiry A
Dental Materials Journal 32(3), 519-521, 2013
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