From the discussion above it is apparent that objectives are the single most important element of a microscope. It is for this reason that so much effort is invested in making sure that they are well-labeled and suited for the task at hand.

Kohärentes Licht Laser

2 zeigt eine Skizze des verwendeten. Interferometers. Zur Justage wird als Lichtquelle ein LASER verwendet. Laserstrahlen sind gefährlich! •. Blicken Sie nie in ...

World-class Nikon objectives, including renowned CFI60 infinity optics, deliver brilliant images of breathtaking sharpness and clarity, from ultra-low to the highest magnifications.

Licht, so wie wir es von der Sonne oder Glühlampen kennen, sendet keine kohärente Strahlung aus. Dies liegt daran, dass diese Lichtquellen Licht in alle Richtungen aussenden und nicht nur Licht einer Wellenlänge aussenden, sondern vieler Wellenlängen. Die bekannteste Quelle für kohärentes Licht ist der Laser. Jede “Laserstrahlung” weist eine zeitliche und räumliche Kohärenz auf.

Kohärentes Licht findet Anwendung in Laser-Chirurgie, Laser-Druckern, Laser-Scannern und in der Faser-Optik-Kommunikation.

Kohärentes Licht Wirkung

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Ein Laser ist ein Gerät, das kohärentes Licht erzeugt, indem es eine stimulierte Emission von Photonen aus einem angeregten Medium erzeugt, wodurch eine einheitliche Wellenfront mit gleichbleibender Phase entsteht.

Kohärentes Licht ist die Voraussetzung, um Interferenz zu erzeugen (und alle damit verbundenen physikalischen “Phänomene”). Oft wird kohärentes Licht mit monochromatischem Licht gleichgesetzt, was nicht ganz korrekt ist. Kohärentes Licht ist eine elektromagnetische Welle mit nur einer bestimmten “Wellenlänge” (=> einfarbiges Licht). Im Gegensatz zu monochromatischem Lichtbesteht zwischen den einzelnen Wellen (zusätzlich) eine feste Phasenverschiebung.

Im Fach Physik wird kohärentes Licht noch enger definiert. Kohärentes Licht ist eine elektromagnetische Strahlung, wobei die Wellenfronten eine festen räumlichen und zeitlichen Zusammenhang aufweisen. Die räumliche Kohärenz liegt vor, wenn alle Wellenfronten die gleiche Ausbreitung haben (feste Phasenbeziehung), während zeitliche Kohärenz vorliegt, wenn alle “Wellenfronten” die gleiche Wellenlänge haben. Erst dann wird in der Physik von kohärentem Licht gesprochen.

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Zeitliche Kohärenz

Wie eingangs erwähnt, handelt es sich bei kohärentem Licht um eine elektromagnetische Strahlung mit einer bestimmten Wellenlänge und einer bestimmten Phasenverschiebung. Darin besteht auch der Unterschied zwischen monochromatischem Licht und kohärentem Licht. Dies lässt sich auch durch das Fremdwort “kohärent” ableiten. Die Bezeichnung “kohärent” leitet sich aus dem Lateinischen und bedeutet sinngemäß “zusammenhängend”. Bei einem kohärenten Licht liegt also ein “Zusammenhang” zwischen den einzelnen Wellenfronten bzw. Wellenzügen vor (=> feste Phasenverschiebung)

Kohärentes Licht findet Anwendung in der Laseraugen-Chirurgie, bei der präzise Schnitte in der Netzhaut gemacht werden müssen.

Kohärenz Psychologie

Glass Design - The quality of glass formulations has been paramount in the evolution of modern microscope optics. Numerous designs have been implemented by a variety of manufacturers, but we will limit this discussion to a specialized low dispersion glass formulation. Extra Low Dispersion (ED) glass was introduced as a major advancement in lens design with optical qualities similar to the mineral fluorite but without its mechanical and optical demerits. This glass has allowed manufacturers to create higher quality objectives with lens elements that have superior corrections and performance.

Most manufacturers have now transitioned to infinity-corrected objectives that project emerging rays in parallel bundles from every azimuth to infinity. These objectives require a tube lens in the light path to bring the image into focus at the intermediate image plane. Infinity-corrected and finite-tube length microscope objectives are not interchangeable and must be matched not only to a specific type of microscope, but often to a particular microscope from a single manufacturer. For example, Nikon infinity-corrected objectives arenot interchangeable with Olympus infinity-corrected objectives, not only because of tube length differences, but also because the mounting threads are not the same pitch or diameter. Objectives usually contain an inscription denoting the tube focal length correction as will be discussed.

Kohärentes Licht beschreibt eine Lichtquelle, bei der die Lichtwellen in einer konstanten Phase zueinander stehen. Das bedeutet, die Phasenverschiebung zwischen den Wellen ändert sich nicht mit der Zeit.

2015327 — The NA of an objective is the simply the ability of the lenses to collect light at a fixed distance from the sample which you are viewing.

Oct 7, 2024 — UV filters in photography are transparent filters that are attached to the front of a camera lens to block out ultraviolet (UV) light. The ...

Other features found on specialized objectives are variable working distance (LWD) and numerical aperture settings that are adjustable by turning the correction collar on the body of the objective as illustrated in Figure 2. The plan fluor objective on the left has a variable immersion medium/numerical aperture setting that allows the objective to be used with multiple different immersion media, including oil, water, and glycerin. The plan apo objective on the right has an adjustable working distance control (termed a "correction collar") that allows the objective to image specimens through glass coverslips of variable thickness. This is especially important in dry objectives with high numerical aperture that are particularly susceptible to spherical and other aberrations that can impair resolution and contrast when used with a cover glass whose thickness differs from the specified design value.

Kohärentes Licht ist für die Datenübertragung effizienter, weil das Signal stärker und zentriert ist, es ermöglicht eine schnellere und klarere Übertragung von Informationen.

Räumliche Kohärenz

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Kohärenz Beispiele

Apr 19, 2019 — The total spectrum of infrared wavelength ranges from about 700 nanometers (nm) to 1 millimeter (mm). Compared to other types of light and ...

Before purchasing or using a microscope, it is important to know the functions of each part. Eyepiece Lens: the lens at the top that you look through. They are ...

Kohärentes Licht hat Wellen, die in einem konstanten Phase-Verhältnis zueinander stehen, während bei inkohärentem Licht die Phasenbeziehungen zufällig sind und das Wellenmuster unregelmäßig ist.

Zeitliche und räumliche Kohärenz

Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.

In der Kommunikation, besonders in der Faseroptik, ermöglicht kohärentes Licht die Übertragung von Daten über große Entfernungen ohne signifikanten Signalverlust.

The objective depicted on the left in Figure 3 has a parfocal distance of 45mm and is labeled with an immersion medium color code in addition to the magnification color code. Parfocal distance is measured from the nosepiece objective mounting hole to the point of focus on the specimen as illustrated in the figure. The objective on the right in Figure 3 has a longer parfocal distance of 60 millimeters, which is the result of its being produced to the Nikon CFI60 200/60/25 Specification, again deviating from the practice of other manufacturers such as Olympus and Zeiss, who still produce objectives with a 45mm parfocal distance. Most manufacturers also make their objective nosepieces parcentric, meaning that when a specimen is centered in the field of view for one objective, it remains centered when the nosepiece is rotated to bring another objective into use.

Special Features - Objectives often have additional special features that are specific to a particular manufacturer and type of objective. The plan apochromat objective illustrated in Figure 1 has a spring-loaded front lens to prevent damage when the objective is accidentally driven onto the surface of a microscope slide.

Some objectives specifically designed for transmitted light fluorescence and darkfield imaging are equipped with an internal iris diaphragm that allows for adjustment of the effective numerical aperture. Abbreviations inscribed on the barrel for these objectives include I, Iris, and W/Iris. The 60x apochromat objective illustrated above has a numerical aperture of 1.4, one of the highest attainable in modern microscopes using immersion oil as an imaging medium.

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Although not common today, other types of adjustable objectives have been manufactured in the past. Perhaps the most interesting example is the compound "zoom" objective that has a variable magnification, usually from about 4x to 15x. These objectives have a short barrel with poorly designed optics that have significant aberration problems and are not very practical for photomicrography or serious quantitative microscopy.

There is a wealth of information inscribed on the barrel of each objective, which can be broken down into several categories. These include the linear magnification, numerical aperture value, optical corrections, microscope body tube length, the type of medium the objective is designed for, and other critical factors in deciding if the objective will perform as needed. A more detailed discussion of these properties is provided below and in links to other pages dealing with specific issues.

Parfocal Distance - This is another specification that can often vary by manufacturer. Most companies produce objectives that have a 45 millimeter parfocal distance, which is designed to minimize refocusing when magnifications are changed.

Kurz nochmal zum Unterschied monochromatisches und kohärentes Licht: Positionieren wird vor einer Glühlampe einen Farbfilter, der nur noch elektromagnetische Strahlung einer Wellenlänge durchlässt, so erhalten wir monochromatisches Licht. Das “einfarbige” Licht ist nun zeitlich kohärent (gleiche Wellenlänge), die Ausbreitung der Wellenlängen im Raum hat aber noch keine feste Phasenbeziehung. Daher gilt, dass kohärentes Licht auch monochromatisches Licht darstellt, während monochromatisches Licht nicht immer kohärent sein muss. Dies kann man aber bei monochromatischen Licht auch erreichen, beispielsweise, indem man eine Blende vor den Farbfilter positioniert und somit die Wellenzüge (der ausbreitenden Wellen) in Phase bringt.

Identification of the properties of individual objectives is usually very easy because important parameters are often inscribed on the outer housing (or barrel) of the objective itself as illustrated in Figure 1. This figure depicts a typical 60x plan apochromat objective, including common engravings that contain all of the specifications necessary to determine what the objective is designed for and the conditions necessary for proper use.

The interactive tutorial above allows the visitor to adjust the correction collar on a microscope objective. There are some applications that do not require objectives to be corrected for cover glass thickness. These include objectives designed for reflected light metallurgical specimens, tissue culture, integrated circuit inspection, and many other applications that require observation with no compensation for a cover glass.

Microscope manufacturers offer a wide range of objective designs to meet the performance needs of specialized imaging methods, to compensate for cover glass thickness variations, and to increase the effective working distance of the objective. Often, the function of a particular objective is not obvious simply by looking at the construction of the objective. Finite microscope objectives are designed to project a diffraction-limited image at a fixed plane (the intermediate image plane), which is dictated by the microscope tube length and located at a pre-specified distance from the rear focal plane of the objective. Microscope objectives are usually designed to be used with a specific group of oculars and/or tube lenses strategically placed to assist in the removal of residual optical errors. As an example, older Nikon and Olympus compensating eyepieces were used with high numerical aperture fluorite and apochromatic objectives to eliminate lateral chromatic aberration and improve flatness of field. Newer microscopes (from Nikon and Olympus) have objectives that are fully corrected and do not require additional corrections from the eyepieces or tube lenses.

Nov 9, 2024 — It is to further enlarge the real image that has been magnified by the objective lens and has a clear resolution, to the extent that the human ...

Kohärenz einfach erklärt

Investigate how internal lens elements in a high numerical aperture dry objective may be adjusted to correct for fluctuations in coverslip thickness.

To attain higher working numerical apertures, many objectives are designed to image the specimen through another medium that reduces refractive index differences between glass and the imaging medium. High-resolution plan apochromat objectives can achieve numerical apertures up to 1.40 when the immersion medium is special oil with a refractive index of 1.51. Other common immersion media are water and glycerin. Objectives designed for special immersion media usually have a color-coded ring inscribed around the circumference of the objective barrel as listed in Table 3 and described below. Common abbreviations are: Oil, Oel (oil immersion), HI (homogeneous immersion), W, Water, Wasser (water immersion), and Gly (glycerol immersion).

Das Licht von einer Glühbirne ist nicht kohärent, weil die Lichtwellen in zufälligen Phasenbeziehungen zueinander emittiert werden.

Multilayer Coatings - Quality microscope objectives are protected and enhanced by unique high-transmission anti-reflective multilayer coatings that are applied to the lens air-interface surfaces to reduce flare and ghosts and ensure high-contrast images. These specialized coatings are also used on the phase plates in phase contrast objectives to maximize contrast.