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Field Lens
In imaging optics, a field lens is a positive-powered lens or group of lenses that comes after the objective lens and before the image plane or the eyepiece, serving to change the size of the image or to provide image-space telecentricity. It is used for the reduction of detector size and, in instances needing high optical gain factor, it can correct aberrations through its several elements. Optical systems that feature multiple image planes are at risk of a potential problem, which involves the inability on the part of succeeding relay lenses to capture a cone of light from the primary objective lens. The field lens - by behaving as a variably angled lens - solves this problem by bending or refracting the cone of light back into the succeeding relay lens. In X-Ray microscopy, the field lens is used to produce parallel and homogeneous illumination of the stencil Stencilling produces an image or pattern on a surface, by applying pigment to a surface through an intermediate obje ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Objective Lens
In optical engineering, the objective is the optical element that gathers light from the object being observed and Focus (optics), focuses the ray (optics), light rays to produce a real image. Objectives can be a single Lens (optics), lens or mirror, or combinations of several optical elements. They are used in microscopes, binoculars, telescopes, cameras, slide projectors, CD players and many other optical instruments. Objectives are also called object lenses, object glasses, or objective glasses. Microscope objectives 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. Magn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Image Plane
In 3D computer graphics, the image plane is that plane in the world which is identified with the plane of the display monitor used to view the image that is being rendered. It is also referred to as screen space. If one makes the analogy of taking a photograph to rendering a 3D image, the surface of the film is the image plane. In this case, the viewing transformation is a projection that maps the world onto the image plane. A rectangular region of this plane, called the viewing window or viewport, maps to the monitor. This establishes the mapping between pixels on the monitor and points (or rather, rays) in the 3D world. The plane is not usually an actual geometric object in a 3D scene, but instead is usually a collection of target coordinates or dimensions that are used during the rasterization process so the final output can be displayed as intended on the physical screen. In optics, the image plane is the plane that contains the object's projected image, and lies beyond the ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eyepiece
An eyepiece, or ocular lens, is a type of lens that is attached to a variety of optical devices such as telescopes and microscopes. It is named because it is usually the lens that is closest to the eye when someone looks through the device. The objective lens or mirror collects light and brings it to focus creating an image. The eyepiece is placed near the focal point of the objective to magnify this image. The amount of magnification depends on the focal length of the eyepiece. An eyepiece consists of several "lens elements" in a housing, with a "barrel" on one end. The barrel is shaped to fit in a special opening of the instrument to which it is attached. The image can be focused by moving the eyepiece nearer and further from the objective. Most instruments have a focusing mechanism to allow movement of the shaft in which the eyepiece is mounted, without needing to manipulate the eyepiece directly. The eyepieces of binoculars are usually permanently mounted in the binocula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecentricity
A telecentric lens is a special optical lens (often an objective lens or a camera lens) that has its entrance or exit pupil, or both, at infinity. Telecentric lenses are often used for precision optical two-dimensional measurements or reproduction and other applications that are sensitive to the image magnification or the angle of incidence of light. The simplest way to make a lens telecentric is to put the aperture stop at one of the lens's focal points. This makes the chief rays (light rays that pass through the center of the aperture) on the other side of the lens parallel to the optical axis for any point in the field of view. Commercially available telecentric lenses are often ''compound lenses'' that include multiple lens elements, for improved optical performance. Telecentricity is not a property of the lenses inside the compound lens but is established by the location of the aperture stop in the lens. The aperture stop selects the rays that are passed through the lens and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optics
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviolet, and infrared light. Because light is an electromagnetic wave, other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties. Most optical phenomena can be accounted for by using the classical electromagnetic description of light. Complete electromagnetic descriptions of light are, however, often difficult to apply in practice. Practical optics is usually done using simplified models. The most common of these, geometric optics, treats light as a collection of rays that travel in straight lines and bend when they pass through or reflect from surfaces. Physical optics is a more comprehensive model of light, which includes wave effects such as diffraction and interference that cannot be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relay Lens
In optics, a relay lens is a lens or a group of lenses that receives the image from the objective lens and relays it to the eyepiece. Relay lenses are found in refracting telescopes, endoscopes, and periscopes to optically manipulate the light path, extend the length of the whole optical system, and usually serve the purpose of inverting the image. They may be made of one or more conventional lenses or achromatic doublets, or a long cylindrical gradient-index of refraction lens (a GRIN lens). Relay lenses operate by producing intermediate planes of focus. For example, in a SLR camera the zoom lens produces an image plane where the image sensor or photographic film would usually go. If you place another lens with focal length ''f'' at the distance 2''f'' from that image plane and then put an image sensor at 2''f'' beyond that lens, that lens will relay the first image to the second image with 1:1 magnification (see thin lens formula showing that with object distance s=2f fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray Microscope
An X-ray microscope uses electromagnetic radiation in the soft X-ray band to produce magnified images of objects. Since X-rays penetrate most objects, there is no need to specially prepare them for X-ray microscopy observations. Unlike visible light, X-rays do not reflect or refract easily and are invisible to the human eye. Therefore, an X-ray microscope exposes film or uses a charge-coupled device (CCD) detector to detect X-rays that pass through the specimen. It is a contrast imaging technology using the difference in absorption of soft X-rays in the water window region (wavelengths: 2.34–4.4 nm, energies: 280–530 eV) by the carbon atom (main element composing the living cell) and the oxygen atom (an element of water). Microfocus X-ray also achieves high magnification by projection. A microfocus X-ray tube produces X-rays from an extremely small focal spot (5 μm down to 0.1 μm). The X-rays are in the more conventional X-ray range (20 to 300 keV) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stencil
Stencilling produces an image or pattern on a surface, by applying pigment to a surface through an intermediate object, with designed holes in the intermediate object, to create a pattern or image on a surface, by allowing the pigment to reach only some parts of the surface. The stencil is both the resulting image or pattern and the intermediate object; the context in which ''stencil'' is used makes clear which meaning is intended. In practice, the (object) stencil is usually a thin sheet of material, such as paper, plastic, wood or metal, with letters or a design cut from it, used to produce the letters or design on an underlying surface by applying pigment through the cut-out holes in the material. The key advantage of a stencil is that it can be reused to repeatedly and rapidly produce the same letters or design. Although aerosol or painting stencils can be made for one-time use, typically they are made with the intention of being reused. To be reusable, they must remain int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lenses
A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), usually arranged along a common axis. Lenses are made from materials such as glass or plastic, and are ground and polished or molded to a desired shape. A lens can focus light to form an image, unlike a prism, which refracts light without focusing. Devices that similarly focus or disperse waves and radiation other than visible light are also called lenses, such as microwave lenses, electron lenses, acoustic lenses, or explosive lenses. Lenses are used in various imaging devices like telescopes, binoculars and cameras. They are also used as visual aids in glasses to correct defects of vision such as myopia and hypermetropia. History The word ''lens'' comes from '' lēns'', the Latin name of the lentil (a seed of a lentil plant) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
