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Filter is an optical device used to select the required radiation band. A common feature of filters is that no filter can make the imaging of celestial bodies brighter, because all filters will absorb certain wavelengths, making objects darker. Color filter These are flat glass or gelatin sheets of various colors with a transmission bandwidth of hundreds of Angstroms. They are mostly used in broadband photometry or installed in stellar spectrograph to isolate overlapping spectral levels. Its main feature is that the size can be made quite large. Thin film filter Generally, the transmission wavelength is long and is mostly used as infrared filter. The latter is on a certain film base. Principle The filter is made of plastic or glass with special dyes. The red filter can only let the red light pass through, and so on. The transmittance of glass sheet is similar to that of air, and all colored light can pass through, so it is transparent. However, after dyeing with dye, the molecular structure changes, the refractive index also changes, and the passage of some colored light changes. For example, when a white light passes through a blue filter, it emits a blue light, while there are very few green and red light, and most of them are absorbed by the filter. Effect The filter plays a great role. Widely used in photography. Why is the main scene always so prominent in the landscape paintings taken by some photographers and how to do it? This uses filters. For example, if you want to take a yellow flower with a camera, the background is blue sky and green leaves. If you take it as usual, you can't highlight the theme of "yellow flower", because the image of yellow flower is not prominent enough. However, if a yellow filter is placed in front of the lens to block the green light scattered by some green leaves and the blue light scattered by the blue sky, and let a large number of yellow light scattered by yellow flowers pass through, the yellow flowers will be very obvious and highlight the theme of "yellow flowers" Characteristic Its main feature is that the size can be made quite large. Thin film filters are generally used as infrared filters because of their long transmission wavelength. The latter is a low-level, multistage series solid Fabry Perot interferometer by alternately forming metal dielectric metal films or all dielectric films with a certain thickness with high refractive index or low refractive index on a certain substrate by vacuum coating method. The choice of film material, thickness and series mode depends on the required central wavelength and transmission bandwidth λ determine. Wavelength Capable of any wavelength from ultraviolet to infrared λ Various interference filters of 1 ~ 500 Angstroms. The peak transmittance of metal dielectric film filter is not as high as that of full dielectric film, but the secondary peak and sideband problems of the latter are more serious. There is also a circular or strip-shaped variable interference filter in the thin-film interference filter, which is suitable for space astronomical measurement. In addition, there is a two-color filter, which is placed at an angle of 45 ° with the incident beam and can decompose the beam into two different colors with mutually perpendicular directions with high and uniform reflection and transmittance, which is suitable for multi-channel and multi-color photometry. The interference filter is generally required to be incident vertically. When the incident angle increases, it moves to the short wave direction. This feature can be used to adjust the central wavelength in a certain range. because λ And peak transmittance vary significantly with temperature and time. Care must be taken when using narrow-band filters. Because it is difficult to obtain large-size uniform film, the diameter of interference filter is generally less than 50mm. Some people have used the splicing method to obtain interference filters as large as 38 cm square, which are installed on the British 1.2-meter Schmidt telescope to take monochromatic images of large-area nebulae.

Cylindrical lens is an aspherical lens, which can effectively reduce spherical aberration and chromatic aberration. It is divided into flat convex cylindrical lens, flat concave cylindrical lens, biconvex cylindrical lens, double concave cylindrical lens, meniscus cylindrical lens, cylindrical intersection cylindrical lens and special-shaped cylindrical lens. It has one-dimensional amplification function. Cylindrical lens is mainly used to change the design requirements of imaging size. For example, convert a point spot into a line spot, or change the height of the image without changing the image width. It can be used in linear detector lighting, bar code scanning, holographic lighting, optical information processing, computer and laser emission. Optical cylindrical mirror is also widely used in high-power laser system and synchrotron radiation beam line. At the same time, the requirements for cylindrical mirror parts are becoming higher and higher, especially in high-precision testing instruments and devices such as cavity plate of high-power laser resonator and long-distance off-line interferometer. Manufacture of cylindrical lens Including rough grinding, fine grinding, polishing, centering and edging.

Prism, a transparent object surrounded by two intersecting planes that are not parallel to each other, used for splitting or dispersing light beams. Prism is a polyhedron made of transparent materials (such as glass, crystal, etc.). It is widely used in optical instruments. Prisms can be divided into several types according to their properties and applications. For example, in spectral instruments, the "dispersion prism" that decomposes the composite light into spectrum is more commonly used as equilateral prism; In periscope, binocular telescope and other instruments, changing the direction of light to adjust its imaging position is called "total reflection prism", which generally adopts right angle prism. Function of reflection prism: when the reflection prism (or reflector) is used as the reflector for ranging, the reflection prism receives the optical signal sent by the total station and reflects it back. The total station sends out the optical signal, receives the optical signal reflected from the reflecting prism, calculates the phase shift of the optical signal, so as to indirectly obtain the time of light passing, and finally measure the distance from the total station to the reflecting prism. Principle of reflection prism: the working principle of reflection prism is actually the reflection law and refraction law of light. When light is reflected in the same medium, its reflection angle is equal to the incident angle; When light is incident from one medium perpendicular to two medium planes to another medium, it will not be refracted.

A lens is made by grinding a transparent material such as glass into a circular sheet so that both surfaces are curved or one side is flat. Its function is to make the beam converge or diverge through the refraction of its two surfaces, and form the image of the object at any required position. Double glue lens is a lens obtained by gluing two lenses together. The combined lens formed by two lenses is an effective method to obtain short focal length, large magnification and better imaging quality. It has been widely used in astronomical telescopes and cameras. Optical microscopy is an ancient subject that has been studied for more than a century. The non-destructive nature of optical microscopy is important in various fields, such as biology and material science. The main disadvantage of ordinary optical microscope is that the resolution is limited by the diffraction limit, and its resolution is an order of magnitude with the illumination wavelength; Another limitation is its limited focal depth. These limitations make it difficult to image objects with a certain thickness using ordinary optical microscopy, so three-dimensional (3D) imaging of thick samples is impossible. In order to improve the resolution of ordinary lens and facilitate confocal 3-D imaging and high-density optical storage, many techniques of super-resolution are proposed by adding pupil filter to the lens of optical system. Such as ring with central occlusion, light leakage ring pupil, phase pupil and grating, etc. These pupils improve the resolution of 2-D imaging, but due to the extension of the focal depth in the axial direction, it is not suitable for confocal 3-D imaging. In addition, due to the method of adding pupil to the lens, the intensity of the light spot is reduced, some even more than 90%, which greatly reduces the signal-to-noise ratio of the optical system. The combined lens formed by two lenses is an effective method to obtain short focal length, large magnification and better imaging quality. This method has been widely used in astronomical telescopes and cameras. In 1990, Mansfield et al. Applied two separate lenses (they are called solid immersion lenses) to near-field light storage, and proved that placing a hemispherical solid immersion lens on the imaging surface of the lens can improve the transverse resolution of the microscope by N times (n is the refractive index of the solid immersion lens). Recently, many literatures have further studied the lateral resolution and polarization characteristics of solid immersion lens, and some literatures use two separate lenses to obtain high numerical aperture lens to improve the resolution of optical system,. The diffraction imaging characteristics of two closely glued double glued thin lenses are analyzed by scalar diffraction theory. It is found that it has not only better transverse resolution, but also higher axial resolution. It can be used as an ideal optical element for confocal 3-D imaging.

An optical lens is a transparent optical component used to converge or diverge light emitted from a peripheral object. The transmitted light rays then form a real or virtual image of the object. Lenses are a good example of transmissive optical components, meaning that they pass or transmit light. Other transmissive components include filters, windows, flats, prisms, beamsplitters, and waveplates, while the opposite category - reflectives (which reflect light rather than transmit it) - include optical mirrors and retroreflectors. Optical lenses have been used since at least c. 700 BCE for a variety of applications, including: Magnification Correction of optical aberrations Use as a firestarter (burning-glasses) Image focusing Image projection Hanzhong Hengpu designs and manufactures optical lenses for industrial, medical, high tech and electronic applications. Standard and custom lens assemblies for scanners, CCTV, CCD/CMOS, medical imaging, surveillance systems, machine vision and night vision systems. Universe Kogaku`s lens application engineers provide your optimal lens solution. We`ll assist you with all of your design considerations-from lens assembly and overall design specifications to budgets and timetables. And we can reduce your project costs with our extensive selection of standard lens assemblies and elements, value-added services for component modification, and with custom designs that often eliminate the need for other components or modifications in your design.

The lens is an optical element with a spherical surface made of transparent material. The lens is composed of several lenses, There are plastic lenses and glass lenses Glass lens is more expensive than plastic lens. Generally, the lens structures used for cameras are: 1p, 2p, 1g1p, 1g2p, 2g2p, 4G, etc. The more lenses, the higher the cost. Therefore, a good quality camera should use glass lens, which has better imaging effect than plastic lens, and plays an important role in astronomy, military, transportation, medicine, art and other fields. concept Lens can be widely used in security, vehicle, digital camera, laser, optical instrument and other fields. With the continuous development of the market, lens technology is more and more widely used. (lens) a lens is made according to the refraction law of light. A lens is an optical element made of transparent substances (such as glass, crystal, etc.). A lens is a refractor, and its refracting surface is a transparent body with two spherical surfaces (part of the spherical surface), or a spherical surface (part of the spherical surface) and a flat surface. Its image has both real and virtual images. Convex lens: thick in the middle and thin at the edge, including biconvex, flat convex and concave convex; Concave lens: thin in the middle and thick at the edge, including double concave, flat concave and convex concave. Little formula 1. Lens The lens can transmit light; Middle thick, convex lens; Thin, concave lens in the middle. Convergent convex lens, divergent concave lens. The flat light converges to a point, represented by focus F. The distance from the focal point to the optical center of the mirror is called the focal length of the mirror (expressed by F). 2. Lens in life The object is far like a close camera, the real image is reduced and inverted. Object near image far projector, enlarge the real image and stand upside down. A magnifying glass on the same side of the object image magnifies a virtual image upright. The real image is inverted, the virtual image is positive, and the virtual image on the opposite side of the real image is the same. 3. Convex lens imaging law and Application The object is imaged between one and two times (focal length) beyond twice the focal length. The real image is inverted and reduced. This example is used in the camera. Things move closer, images move farther, and images get bigger. The object is imaged outside the double focal length between one and two times the distance. The real image is inverted and enlarged. This example is used in the projector. The object is in the focus, and the moving light screen does not see the image. Look at the object through the lens and enlarge a virtual image upright. The object is on the same side as the image. This example is used for a magnifying glass. The near image and the far image of the object become larger, and the far image and the near image of the object become smaller. Twice the focal length is divided into size, and twice the focal length is divided into virtual and real. As the object distance decreases, the real image becomes larger and farther, and the virtual image becomes smaller and closer. Explanation: When the object is outside the focal length of the convex lens, the convex lens becomes a real image. When the object is outside the double focal length of the convex lens (U > 2f), the convex lens becomes a reduced real image. When 2F > U > F, it becomes an enlarged real image. The virtual image and real image without reduction are inverted, and there is no inverted virtual image. expand The knowledge points about lens and its application expansion in the junior middle school applied physics knowledge competition mainly include: 1. Three principles (three special rays) for lens imaging mapping: ① the light parallel to the main optical axis passes through the main focus after being refracted by the lens; ② the direction of the light passing through the optical center remains unchanged after being refracted by the lens; ③ the light passing through the main focus is refracted by the lens and then parallel to the main optical axis. 2. Convex lens imaging formula: 1 / u (object distance) + 1 / V (image distance) = 1 / F (lens focal length). Understanding of convex lens imaging law: a) One conclusion: reality is different, deficiency is the same. That is, the real image is always upside down on the opposite side, which can not only be seen, but also be carried on with a light screen; The virtual image is always standing on the same side, which can be seen, but can not be carried on with a light screen. b) Two dividing points: focus and 2x focal length. Focus is the dividing point between real image and virtual image. When the object is within the focus of the convex lens, it becomes a virtual image; When the object is outside the focus of the convex lens, it becomes a real image. It can be abbreviated as: the focus is divided into internal and external virtual reality, internal virtual and external reality. The point at twice the focal length is the dividing point between the enlarged image and the reduced image. When the object is located between 2 times the focal length and the focus of the convex lens, it becomes an enlarged real image; When the object is located outside the focal length of the convex lens, it becomes a reduced real image. It can be abbreviated as: 2 times the focal length, the point is divided inside and outside, the inside is large and the outside is small. Three changes: ① changes in image size and image distance: when the object moves closer to the focus, the image becomes larger and the image distance becomes larger. ② Change of image object moving speed: the object is located outside the point at twice the focal length (U > 2f), the object distance is greater than the image distance, the real image is reduced upside down, and the object moving speed is greater than the image moving speed; the object is located between the point and the focus at twice the focal length (f < U < 2f), when the object distance is less than the image distance, it becomes an inverted enlarged real image, and the moving speed of the object is less than the moving speed of the image. ③ distance change between objects and images: when the object is located at 2 times the focal length, the imaging is at 2 times the focal length on the other side, the object image distance is the smallest, which is equal to 4 times the focal length. When the object is located outside the 2 times the focal length, the imaging is between the focal point on the other side and the 2 times the focal length, and the object moves towards 2 times the focal length When the point moves, the distance between objects and images becomes smaller; When the object moves away from the point at twice the focal length, the distance between objects and images becomes larger. When the object is located within the 2x focal length (between the focus and the point at the 2x focal length), the imaging is outside the 2x focal length on the other side, the object moves to the point at the 2x focal length, and the distance between objects and images becomes smaller; when the object moves to the focus, the distance between objects and images becomes larger. The object lens is a final electromagnetic lens that focuses the electron beam on the substrate [1].