• WordNet 3.6
    • n radiometer meter to detect and measure radiant energy (electromagnetic or acoustic)
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Webster's Revised Unabridged Dictionary
    • Radiometer (Naut) A forestaff.
    • Radiometer (Physics) An instrument designed for measuring the mechanical effect of radiant energy.
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Century Dictionary and Cyclopedia
    • n radiometer An old instrument for measuring angles; the cross-staff. The end of the staff was held to the eye, and the crosspiece was shifted until it just covered the angle to be measured, when the latter was read off on the longitudinal staff.
    • n radiometer An instrument which serves to transform radiant energy into mechanical work. It consists of four crossed arms of very fine glass, supported in the center by a needle-point, and having at the extreme ends thin vertical disks or squares of pith, blackened on one side. When placed in a glass vessel nearly exhausted of air, and exposed to rays of light or heat, the blackened surfaces absorb the radiant energy and become heated, the molecules of the air remaining in the vessel striking against them gain from them greater velocity and there results an increased pressure, causing a more or less rapid revolution of the arms. By varying the conditions as to degree of exhaustion, size of bulb, etc., a number of experiments are performed with the radiometer which serve to illustrate the mechanical effects of the rapidly moving molecules of a gas.
    • n radiometer An instrument for the detection and measurement of small amounts of radiant energy. An adaptation of Crookes's form of radiometer to delicate heat-measurements has more recently been devised by E. F. Nichols. The Nichols radiometer has two vanes at the ends of a short cross-arm, suspended by a quartz fiber in vacuo. In order to protect the instrument from the effects of stray heat, the containing-vessel is usually of metal, with a window of transparent rock-salt or fiuorite for the admission of the radiation to be measured, and a second window of glass through which the angular movement of a light mirror attached to the suspended parts may be observed. The construction of the radiometer varies considerably according to the work for which it is designed. The form of instrument constructed for the measurement of the heat of the fixed stars is shown in Fig. 1. The vanes D, D and the mirror M, the plane of which is perpendicular to that of the vanes, are mounted upon a fine rod of drawn glass, AB, the upper end of which is attached to a very fine quartz fiber, 32 millimeters long, BC. The vanes are disks of thin mica coated with lampblack and about 2 millimeters in diameter. The distance between the centers of the vanes is 4.5 millimeters. The mirror, which is 3 × 2 millimeters, consists of a silvered portion of thin microscope-cover glass. The apparatus is essentially a torsion balance, the mass (about 6 milligrams) and moment of inertia of which are exceedingly small. When radiation passing through the fluorite window F (Fig. 2) falls upon one of the vanes, the vane is repelled, and the balance revolves through an angle such that the torsional elasticity of the quartz fiber precisely counteracts the torque due to radiation. The deflection thus produced is measured by observing the angular movement of a beam of light reaching the mirror M through the window W (indicated in the diagram by the dotted circle). The sensitiveness of this form of radiometer and of the corresponding forms used in the exploration of the spectrum is greater than that of any other device known to the physicist. It was found possible, for example, to measure the heat received from Arcturus, which is approximately equal to the one hundred-millionth part of that from a candle at a distance of one meter, and even the heat from Vega, which is only half as bright as Arcturus. The sensitiveness of the radiometer varies with the pressure of the gas in which the vanes are suspended, reaching a maximum at a pressure of about .05 millimeters. It also depends upon the distance between the vanes and the fluorite window. The best effect is produced when this window is within two or three millimeters of the vanes, as shown in Fig. 2.
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Chambers's Twentieth Century Dictionary
    • Radiometer an instrument consisting of four horizontal arms of very fine glass, carefully poised so as to revolve easily on a point, the whole contained in a glass vessel almost exhausted of air—the arms move round under light or heat, more or less swiftly according to the strength of the rays
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Webster's Revised Unabridged Dictionary
L. radius, radius + -meter,: cf. F. radiomètre,


In literature:

Instead of using the fan in this experiment, we may use the "electric" radiometer with similar effect.
"Experiments with Alternate Currents of High Potential and High Frequency" by Nikola Tesla
The monitors were synchronized with the radiometer and changed view at every ten-mile marker.
"Code Three" by Rick Raphael
And now, as we view the radiometer, the scene shifts by yet another century, and we come out of cloud-land and into our own proper age.
"A History of Science, Volume 5(of 5)" by Henry Smith Williams
Count Bathyani recently took up a radiometer to a height of about a mile.
"The Galaxy, April, 1877" by Various
The spectroscope and the radiometer are more wonderful than any 'supernatural' thing yet heard of.
"British Goblins" by Wirt Sikes
"The Galaxy" by Various
"Scientific Culture, and Other Essays" by Josiah Parsons Cooke
Instead of using the fan in this experiment, we may use the "electric" radiometer with similar effect.
"The inventions, researches and writings of Nikola Tesla" by Thomas Commerford Martin
Upon the benches stood some strange-looking wireless condensers, radiometers, detectors and other objects which we had constructed.
"The Zeppelin Destroyer" by William Le Queux

In news:

Spectronics Corporation has introduced the feature-enriched Spectroline® AccuMAX XRP-3000 digital radiometer/ photometer , the new benchmark in light measurement technology for NDT.
Spectronics Corporation has introduced the feature-enriched Spectroline® AccuMAX XRP-3000 digital radiometer /photometer, the new benchmark in light measurement technology for NDT.
Danaher Buys Radiometer , Gendex Dec 12, 2003 Printable format Email this Article Search.
One of the instruments aboard, the Diviner Lunar Radiometer Experiment, will make the first global survey of the temperature of the lunar surface while the orbiter circles some 31 miles (50 kilometers) above the Moon.
The effort took 312 orbits to get "a clear shot of every parcel of Earth 's land surface and islands," and a powerful Visible Infrared Imaging Radiometer Suite sensor to capture 2.5 terabytes of pictures.
The Suomi NPP satellite has used its Visible Infrared Imaging Radiometer Suite instrument to record city lights in the United States and elsewhere around the globe.
The new data from NASA was mapped over existing Blue Marble imagery of Earth to provide a realistic view of the planet, made possible by the new "day-night band" of the Visible Infrared Imaging Radiometer Suite (VIIRS).
This image is a fish-eye projection taken with the descent imager/spectral radiometer onboard the European Space Agency's Huygens probe, when the probe was about 3 miles (5 kilometers) above Titan 's surface.
This short animation is made up from a sequence of images taken by the Descent Imager/Spectral Radiometer (DISR) instrument on board ESA's Huygens probe, during its successful descent to Titan on Jan 14, 2005.
Consistent curing requires consistent light intensity, according to Dymax, maker of the new ACCU-CAL 50V radiometer designed to offer repeatable measurement of visible light.
The radiometer can measure visible light energy emitted from lightguides (3 mm, 5 mm, and 8 mm), flood systems, and conveyors.

In science:

For each of the WMAP frequencies and each of the components (CMB, synchrotron, free-free, thermal and spinning dust) PSM provides maps without observational errors and no corrections for the angular resolution of the different radiometers.
Foreground removal from WMAP 5yr temperature maps using an MLP neural network
All observations were corrected for atmospheric absorption through use of the CSO radiometers.
Mid-J CO Emission From NGC 891: Microturbulent Molecular Shocks in Normal Star Forming Galaxies
Here σrn , σJ , and σscint represent the uncertainties contributed by radiometer noise, pulse phase jitter and interstellar scintillation, respectively, which can be calculated by following e.g.
Prospects for Probing the Spacetime of Sgr A* with Pulsars
The general experimental concept is to observe the total power coming from the sky and compare that to a well known reference source using specially designed radio receivers called radiometers.
The Cosmic Microwave Background Spectrum
The references we used were carefully designed blackbodies with total temperature of about 3.8 K which was very close to the total sky signal so that the gain calibration of our radiometers was not a critical component of the observation.
The Cosmic Microwave Background Spectrum