| Your doctor may use a computerized refractor to measure your eyes and estimate the prescription you need to correct a refractive error. |
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| A heliometer is a refractor, with the objective cut in two, which was used to measure small angular distances. |
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| One evening he was observing with a rather crude refractor, with a focal length of 24 feet. |
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| At the same site you can take a virtual tour of the observatory and its telescope, whose refractor is still the largest of its kind in the world. |
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| If you are buying a refractor, don't go for an objective smaller than 75 mm. |
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| In a refractor the first lens through which light from a celestial object passes is called the objective lens. |
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| A lower reflector and a refractor situated in the base of the bowl give complete control over the effects of glare. |
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| In its lower part, the base of the luminaire houses a reflector and a prismatic refractor. |
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| Orion refractor telescope — a tool, built for astrophotography, that Paglen frequently uses to take pictures. |
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| Either a refractor or a reflector may be used for visual observations of solar features, such as sunspots or solar prominences. |
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| Nevertheless, its original 91-cm refractor had been built as a visual instrument and was not suited for photography. |
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| The luminous flux is conducted by the internal surface of the body and then crosses the refractor towards the area to be illuminated. |
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| Thanks to the prismatic refractor, Altra luminaires can be installed with greater spacing, while maintaining high levels of luminance uniformity. |
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| The optical compartment consists of an extruded aluminium reflector, painted white, and an acrylic prismatic refractor. |
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| Thanks to the prismatic refractor, the Aresa luminaire provides a remarkable photometric performance. |
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| A version featuring an optical compartment integrating a refractor is also available as an option. |
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| The refractor protectors allow for extensive distributions, therefore increasing the spacing between columns. |
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| The luminaire uses a larger prismatic polymer refractor to deliver wide low brightness illumination for streets and parking areas. |
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| The refractor is available in clear acrylic polymer or in clear polycarbonate where additional impact resistance is required. |
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| The internal surface of the light conductor element has been treated to distribute the light along the whole length of the refractor, thanks to a high specular reflection coefficient. |
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| Polycarbonate prismatic refractor, with anti-UV treatment. |
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| The optical compartment is comprised of a lower reflector with UV-stabilised moulded polycarbonate refractor and a second reflector beneath the top cover of the luminaire. |
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| A catadioptric telescope design incorporates the best features of both the refractor and the reflector i.e., it has both reflective and refractive optics. |
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| The younger Alvan Clark directed the fabrication of the 40-inch lens of the Yerkes Observatory, Williams Bay, Wis., the largest refractor lens in the world. |
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| Zeekoegat saw the erection of the so-called GPO telescope, a 40 cm objective-prism refractor, for determining radial velocities. |
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| The ordinary sea captain's sort of telescope is of the refractor kind. |
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| The luminous flux is directed by a reflector all the way along the box, which is called the light distributor, before traversing the prisms of the refractor in the direction of the zone to be illuminated. |
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| The optical compartment consists of a white lacquered metallic reflector holding the lampholder support and the lamp, and a prismatic refractor made of polycarbonate, treated to withstand UV rays, or of acrylic. |
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| Later he made micrometrical observations of comets and double stars with the 15-inch refractor in order to determine their orbits. |
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| This principle of lighting is characterised by a beautiful uniformity of light over the entire surface of the refractor and by true visual comfort. |
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| At the observatory we were set up with a 100mm refractor with a solar filter, a 150mm Newtonian reflector and a small Coronado PST solar telescope. |
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