Ophthalmic lens
... Historians credit the Chinese with carving the first frames more than 2,000 years ago, but apparently those frames did not contain lenses and were used to protect their eyes from "evil forces." The frames were carved from tortoiseshell, a sacred material. The use of a magnifying glass was first reco ...
... Historians credit the Chinese with carving the first frames more than 2,000 years ago, but apparently those frames did not contain lenses and were used to protect their eyes from "evil forces." The frames were carved from tortoiseshell, a sacred material. The use of a magnifying glass was first reco ...
The interference characteristics of light
... But the cat-eye optical lens is a non-cooperative target whose parameters are unknown. By using the active laser detection technique based on the theory of cat-eye effect of optical lens, a much larger detection distance and a higher orientation precision can be obtained than that by using passive d ...
... But the cat-eye optical lens is a non-cooperative target whose parameters are unknown. By using the active laser detection technique based on the theory of cat-eye effect of optical lens, a much larger detection distance and a higher orientation precision can be obtained than that by using passive d ...
Conference title, upper and lower case, bolded, 18 point type
... naturally has the characteristics of negligible S and high NA within the above range of 1.5 RIC 1.75 . And only within 1.5 RIC 1.75 , the maximum lateral resolution of the microsphere might be obtained. The above conclusion will further be proved by the FDTD method. Here, the x linearly pola ...
... naturally has the characteristics of negligible S and high NA within the above range of 1.5 RIC 1.75 . And only within 1.5 RIC 1.75 , the maximum lateral resolution of the microsphere might be obtained. The above conclusion will further be proved by the FDTD method. Here, the x linearly pola ...
Microscopes - Photonics Research Group
... a high-vacuum environment and other conditions compatible with electron imaging. Thus, for four decades following World War II, the light microscope in many fields took a back seat to the electron microscope. During the last decade, however, the light microscope has reemerged as an indispensable, po ...
... a high-vacuum environment and other conditions compatible with electron imaging. Thus, for four decades following World War II, the light microscope in many fields took a back seat to the electron microscope. During the last decade, however, the light microscope has reemerged as an indispensable, po ...
Ch 03 - Aberrations
... Coma is a particularly disturbing aberration since its flare is nonsymmetrical. Its presence is very detrimental to accurate determination of the image position since it is much more difficult to locate the “center of gravity” of a coma patch than for a circular blur such as that produced by spheric ...
... Coma is a particularly disturbing aberration since its flare is nonsymmetrical. Its presence is very detrimental to accurate determination of the image position since it is much more difficult to locate the “center of gravity” of a coma patch than for a circular blur such as that produced by spheric ...
All-dielectric subwavelength metasurface focusing lens
... geometric parameters of the fine pattern. The meta-surface thickness is approximately onethird of the free-space wavelength (λ0 = 1.55 μm, and height ≈0.5 μm), in our specific case. Hence, the phase mask depth variation, Δφ ≈2πδn(h/λ0) ~2⋅δn rad < 2π, across the lens area is relatively small. Theref ...
... geometric parameters of the fine pattern. The meta-surface thickness is approximately onethird of the free-space wavelength (λ0 = 1.55 μm, and height ≈0.5 μm), in our specific case. Hence, the phase mask depth variation, Δφ ≈2πδn(h/λ0) ~2⋅δn rad < 2π, across the lens area is relatively small. Theref ...
Aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are, which is of great importance for the appearance at the image plane. If an aperture is narrow, then highly collimated rays are admitted, resulting in a sharp focus at the image plane. If an aperture is wide, then uncollimated rays are admitted, resulting in a sharp focus only for rays with a certain focal length. This means that a wide aperture results in an image that is sharp for things at the correct distance. The aperture also determines how many of the incoming rays are actually admitted and thus how much light reaches the image plane (the narrower the aperture, the darker the image for a given exposure time). In the human eye, the pupil is the aperture.An optical system typically has many openings, or structures that limit the ray bundles (ray bundles are also known as pencils of light). These structures may be the edge of a lens or mirror, or a ring or other fixture that holds an optical element in place, or may be a special element such as a diaphragm placed in the optical path to limit the light admitted by the system. In general, these structures are called stops, and the aperture stop is the stop that determines the ray cone angle, or equivalently the brightness, at an image point.In some contexts, especially in photography and astronomy, aperture refers to the diameter of the aperture stop rather than the physical stop or the opening itself. For example, in a telescope the aperture stop is typically the edges of the objective lens or mirror (or of the mount that holds it). One then speaks of a telescope as having, for example, a 100 centimeter aperture. Note that the aperture stop is not necessarily the smallest stop in the system. Magnification and demagnification by lenses and other elements can cause a relatively large stop to be the aperture stop for the system.Sometimes stops and diaphragms are called apertures, even when they are not the aperture stop of the system.The word aperture is also used in other contexts to indicate a system which blocks off light outside a certain region. In astronomy for example, a photometric aperture around a star usually corresponds to a circular window around the image of a star within which the light intensity is assumed.