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210:. Common lenses are usually entocentric. In particular, a single lens without a separate aperture stop is entocentric. For such a lens the chief ray originating at any point off of the optical axis is never parallel to the optical axis, neither in front of nor behind the lens. A non-telecentric lens exhibits varying
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to adjust the position of the focal plane. Some commercial telecentric lenses, however, do feature a focus ring. This can be used to slightly adjust the working distance and magnification while losing a little bit of telecentricity. Sometimes, manufacturers specify a sensor resolution or pixel size
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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 this specific
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In a bi-telecentric (or double-telecentric) lens, both entrance and exit pupil are at infinity. The magnification is constant despite variations of both the distance of the object being observed and the image sensor from the lens, allowing more precise object size measurements than with a
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for objects at different distances from the lens. An entocentric lens has a smaller magnification for objects farther away; objects of the same size appear smaller the farther they are away. A hypercentric lens produces larger images the farther the object is away.
159:, or both, at infinity. The size of images produced by a telecentric lens is insensitive to either the distance between an object being imaged and the lens, or the distance between the image plane and the lens, or both, and such an optical property is called
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initially required image-space telecentric lenses, but with the improvement of sensors, the angle of incidence requirement has been relaxed. Since every pixel is illuminated at the same angle by an image-space telecentric lens, they are also used for
372:(light rays that pass through the center of the aperture stop) after an image-space telecentric lens are always parallel to the optical axis, these lenses are often used in applications that are sensitive to the angle of incidence of light.
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An image-space telecentric lens has the exit pupil (the image of the aperture stop formed by optics after it) at infinity and produces images of the same size regardless of the distance between the lens and the
234:). In an object-space telecentric lens the image size does not change with the object distance, and in an image-space telecentric lens the image size does not change with the image-side distance from the lens.
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Image-space telecentric imaging where the aperture is in the front focal plane of the objective. The exit pupil is located at infinity, and chief rays after the objective are parallel to the optical axis.
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Object-space telecentric imaging where the aperture is in the back focal plane of the objective. The entrance pupil is located at infinity, and chief rays before the objective are parallel to the optical
190:(light rays that pass through the center of the aperture stop), that will be about parallel to the optical axis on the other side of the lens, to pass the optical system for any object point in the
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Commercial object-space telecentric lenses are often characterized by their magnification, working distance and maximum image circle or image sensor size. A truly telecentric lens has no
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An object-space telecentric lens has the entrance pupil (the image of the lens's aperture stop, formed by optics before it) at infinity and provides an
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for mass semiconductor device production) because small image distortion and placement errors can be critical for manufactured device functionality.
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Because their images have constant magnification and constant viewing angle across the field of view, object-space telecentric lenses are used for
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mono-telecentric lens (i.e., the measurements being insensitive to placement errors of the object and the image sensor). A bi-telecentric lens is
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system must determine the precise size and shape of objects independently from their exact distance and position within the field of view.
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than a smaller lens. Because of their intended applications, telecentric lenses often have higher
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Telecentric lenses tend to be larger, heavier, and more expensive than normal lenses of similar
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Matsuyama, Tomoyuki; Ohmura, Yasuhiro; Williamson, David M. (2006). Flagello, Donis G (ed.).
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are two examples where image-space telecentricity is used. Another example is minimizing
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Large and heavy bi-telecentric lenses with many optical elements are commonly used in
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Bi-telecentric imaging where the aperture is in the common focal plane of two
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and may be blurry but will be the same size regardless of distance.
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for accurate measurements across the entire field of view at great
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Commercial bi-telecentric lenses are often optimized for very low
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Bi-telecentric lens with 208 mm diameter front element and a
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in an entocentric lens. Object-space telecentric lenses have a
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In order to optimize the telecentric effect when objects are
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to describe the optical quality of the lens and the maximum
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The simplest way to make a lens telecentric is to put the
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and transmit more light than normal photographic lenses.
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in the camera. An object that is closer or farther is
194:. Commercially available telecentric lenses are often
457:. These lenses often comprise more than 10 elements.
163:. Telecentric lenses are used for precision optical
392:between pixels in image sensors and maximizing the
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46:. Unsourced material may be challenged and removed.
504:"The Lithographic Lens: its history and evolution"
413:to be the same regardless of the field position.
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267:and imaged sharply onto the image sensor at
199:selection is what makes a lens telecentric.
202:If a lens is not telecentric, it is either
106:Learn how and when to remove this message
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409:applications, where one would need the
334:telecentric (or collimated) illuminator
489:"Micro Four-Thirds and Telecentricity"
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44:adding citations to reliable sources
167:measurements, reproduction (e.g.,
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310:it can achieve due to the lens's
513:. Optical Microlithography XIX.
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263:. Objects at this distance are
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