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Laser Diode

    A laser diode, or LD, is an electrically pumped semiconductor laser in which the active laser medium is formed by a p-n junction of a semiconductor diode similar to that found in a light-emitting diode.     The laser diode is the most common type of laser produced with a wide range of uses that include fiber optic communications, barcode readers, laser pointers, CD/DVD/Blu-ray Disc reading and recording, laser printing, laser scanning and increasingly directional lighting sources. a packaged laser diode shown with a penny for scale. the laser diode chip is removed from the above package and placed on the eye of an needle for scale.       1.0 Theory of operation A laser diode with the case cut away. The actual laser diode chip is the small black chip at the front; a photodiode at the back is used to control output power. SEM (Scanning Electron Mic..

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Posted: 22/03/2016

Spotting Scope

    A spotting scope is a small portable telescope with added optics to present an erect image, optimized for the observation of terrestrial objects. They are used for birdwatching and other naturalist activities, for hunting, verifying a marksman's shots, surveillance, and for any other application that requires more magnification than a pair of binoculars, typically on the order of 20× to 60×.     The light-gathering power and resolution of a spotting scope is determined by the diameter of the objective lens, typically between 50 and 80 mm (2.0 and 3.1 in). The larger the objective, the more massive and expensive the telescope.     The optical assembly has a small refracting objective lens, an image erecting system that uses either image erecting relay lenses or prisms (Porro prisms or roof prisms), and an eyepiece that is usually removable and interchangeable to give different magnifications. Other telescope designs are used such as Schmidt and ..

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Posted: 22/03/2016

Night Vision

    Night vision is the ability to see in low light conditions. Whether by biological or technological means, night vision is made possible by a combination of two approaches: sufficient spectral range, and sufficient intensity range. Humans have poor night vision compared to many animals, in part because the human eye lacks a tapetum lucidum. Two American soldiers pictured during the 2003 Iraq War seen through an image intensifier     1.0 Types of ranges 1.1 Spectral range     Night-useful spectral range techniques can sense radiation that is invisible to a human observer. Human vision is confined to a small portion of the electromagnetic spectrum called visible light. Enhanced spectral range allows the viewer to take advantage of non-visible sources of electromagnetic radiation (such as near-infrared or ultraviolet radiation). Some animals such as the mantis shrimp can see using much more of the infrared and/or ultraviolet..

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Posted: 22/03/2016

Monocular

    A monocular is a modified refracting telescope used to magnify the images of distant objects by passing light through a series of lenses and usually prisms, the application of prisms resulting in a lightweight, compact telescope. Volume and weight are less than half those of binoculars of similar optical properties, making it easy to carry, and also proportionally less expensive. Monoculars produce 2-dimensional images, while binoculars add perception of depth (3 dimensions), assuming one has binocular vision.     Monoculars are ideally suited to those with vision in only one eye, or where compactness and low weight are important (e.g. hiking). However, monoculars are sometimes preferred by those with normal vision, where using both eyes through binoculars causes difficulties.     A monocular with a straight optical path is relatively long; prisms are normally used to fold the optical path to make an instrument which is much shorter (see the entr..

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Posted: 21/03/2016

Zoom Lens

    A zoom lens is a mechanical assembly of lens elements for which the focal length (and thus angle of view) can be varied, as opposed to a fixed focal length (FFL) lens (see prime lens).     A true zoom lens, also called a parfocal lens, is one that maintains focus when its focal length changes. A lens that loses focus during zooming is more properly called a varifocal lens. Despite being marketed as zoom lenses, virtually all consumer lenses with variable focal lengths use varifocal design.     Zoom lenses afford the user the convenience of variable focal length, at the cost of complexity. Zoom lenses achieve this convenience through compromises on image quality, weight, dimensions, aperture, autofocus performance (both speed and accuracy), build quality, and cost of manufacture. For example, all zoom lenses suffer from at least slight, if not considerable, loss of image resolution at their maximum aperture, especially at the extremes of their foc..

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Posted: 21/03/2016

DCHCoast - Astronomical Telescope, Binoculars, Laser Rangefinders, Night Visions, Microscope, Spotting Scope, Rifle Scope