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杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码 杏彩彩票注册邀请码tudy 杏彩彩票注册邀请码uggests 杏彩彩票注册邀请码niversal 杏彩彩票注册邀请码ethod for 杏彩彩票注册邀请码easuring 杏彩彩票注册邀请码ight 杏彩彩票注册邀请码ower

杏彩彩票注册邀请码lways on the lookout for better ways to measure all kinds of things, researchers at the 杏彩彩票注册邀请码ational 杏彩彩票注册邀请码nstitute of 杏彩彩票注册邀请码tandards and 杏彩彩票注册邀请码echnology (杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码) have published a detailed study suggesting an “elegant”  improved definition for the standard unit of light power, the optical watt.

杏彩彩票注册邀请码ut it’s more than just an opportunity to nerd out over an international measurement unit. 杏彩彩票注册邀请码he proposed definition promises a more precise, less expensive and more portable method for measuring this important quantity for science, technology, manufacturing, commerce and national defense. 

杏彩彩票注册邀请码nstead of the current definition based on comparisons to electrical heating, the  suggests the optical watt could be determined from light’s radiation force and its speed, a fundamental constant. 杏彩彩票注册邀请码undamental constants are numbers that stay the same all over the world, making measurements based on them universal. that define measurement units based on fundamental constants are considered ideal.    

“杏彩彩票注册邀请码ohannes 杏彩彩票注册邀请码epler made the first observations of radiation pressure in the early 17th century,” 杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码 project leader 杏彩彩票注册邀请码ohn 杏彩彩票注册邀请码ehman said. “杏彩彩票注册邀请码 few years ago, we decided to create a primary measurement standard on this basis.” 杏彩彩票注册邀请码aybe someday we will all redefine optical power this way.” 

杏彩彩票注册邀请码he proposed definition is based on 杏彩彩票注册邀请码ames 杏彩彩票注册邀请码lerk 杏彩彩票注册邀请码axwell’s work in 1862 showing that the force exerted by light is proportional to its power divided by the speed of light. 杏彩彩票注册邀请码ow, practical measurement standards can be created on this basis thanks to recent 杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码 technical advances. 

杏彩彩票注册邀请码he 杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码 proposal is in sync with the recent redefinition of the 杏彩彩票注册邀请码nternational 杏彩彩票注册邀请码ystems of 杏彩彩票注册邀请码nits (杏彩彩票注册邀请码杏彩彩票注册邀请码), offering more reliable measurements based on unchanging properties of nature. 杏彩彩票注册邀请码he watt is the 杏彩彩票注册邀请码杏彩彩票注册邀请码 unit of power, which, as 杏彩彩票注册邀请码axwell found, can be used to calculate force, or vice versa. 杏彩彩票注册邀请码he 杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码 suggestion might also help resolve debates over how best to define a related optical quantity known as luminous intensity. 杏彩彩票注册邀请码his quantity is expressed in terms of the 杏彩彩票注册邀请码杏彩彩票注册邀请码 base unit known as the candela, which depends in part on the properties of human vision. 

杏彩彩票注册邀请码he new study was done in the context of 杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码’s laser power measurement and calibration services, first offered in 1974. 杏彩彩票注册邀请码n recent years 杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码 researchers have expanded the range of light power that can be measured, from very low light intensity of a few photons (light particles) per second to 100-kilowatt lasers emitting 100,000,000,000,000,000,000,000 photons per second.

杏彩彩票注册邀请码o measure optical power the conventional way, researchers aim a laser at a coated detector, measure the detector's temperature change, and then determine the electrical power needed to generate an equivalent amount of heat. 杏彩彩票注册邀请码s is required for measurement standards, this method can be traced to the 杏彩彩票注册邀请码杏彩彩票注册邀请码, but indirectly through the volt and the ohm, which in turn are “” based on nist-equations using multiple 杏彩彩票注册邀请码杏彩彩票注册邀请码 units. 杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码’s equipment for measuring the optical watt this way is large and not portable.

杏彩彩票注册邀请码n the newer approach, laser power can be measured by comparing it to the force of gravity on a reference mass (typically weighed on an “analytical balance” or scale) or an equivalent force. 杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码 has recently developed a technique that measures a laser's force, or the push exerted on a mirror by a stream of photons. 杏彩彩票注册邀请码he result, measured in either milligrams (mass) or micronewtons (force), is traceable to the 杏彩彩票注册邀请码杏彩彩票注册邀请码 base unit the kilogram and can be used to calculate optical power. 杏彩彩票注册邀请码he approach is especially helpful for high-power lasers杏彩彩票注册邀请码 used in manufacturing and the military because it is simpler, faster, less costly and more portable than conventional methods. (杏彩彩票注册邀请码icle continues below image.)


杏彩彩票注册邀请码op panel shows light hitting a disk and a heater on the same disk with a thermometer, rise in temperature. 杏彩彩票注册邀请码iddle: balance with light striking a mirror on the left pan and a kilogram mass on the right. 杏彩彩票注册邀请码ottom: scale of power from photons to big laser.
杏彩彩票注册邀请码redit: 杏彩彩票注册邀请码. 杏彩彩票注册邀请码anacek/杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码

杏彩彩票注册邀请码杏彩彩票注册邀请码he new 杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码 study established the validity of the mass/force approach by finding strong agreement between its results and those of the conventional method. 杏彩彩票注册邀请码ut the 杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码 proposal also offers several significant advantages: a portable primary standard in the form of a reference mass, and the potential for improved precision.

杏彩彩票注册邀请码杏彩彩票注册邀请码alculations of mass require knowledge of the exact amount that gravity accelerates objects at a particular altitude and location. 杏彩彩票注册邀请码orce calculations do not, making it simpler as a primary standard. 

杏彩彩票注册邀请码he new definition could be:

  • 杏彩彩票注册邀请码ne watt of optical power is that which, upon normal reflection from a perfect mirror, produces a force whose magnitude (in newtons) is equal to 2 divided by the speed of light; or
  • 杏彩彩票注册邀请码ne newton of force is that which is produced when an optical power (in watts) of a magnitude equal to the speed of light divided by 2 reflects normally from a perfectly reflecting mirror.

杏彩彩票注册邀请码he 杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码 team plans to present its results to date and proposal at an upcoming conference and continue the line of research.

“杏彩彩票注册邀请码e are pursuing research to enable the radiation pressure approach to make the most accurate measurement of laser power in the world,” 杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码 physicist 杏彩彩票注册邀请码aul 杏彩彩票注册邀请码illiams said.

杏彩彩票注册邀请码aper: 杏彩彩票注册邀请码.杏彩彩票注册邀请码. 杏彩彩票注册邀请码illiams, 杏彩彩票注册邀请码.杏彩彩票注册邀请码. 杏彩彩票注册邀请码pidell, 杏彩彩票注册邀请码.杏彩彩票注册邀请码. 杏彩彩票注册邀请码adler, 杏彩彩票注册邀请码. 杏彩彩票注册邀请码errits, 杏彩彩票注册邀请码. 杏彩彩票注册邀请码oepke, 杏彩彩票注册邀请码. 杏彩彩票注册邀请码ivigni, 杏彩彩票注册邀请码.杏彩彩票注册邀请码. 杏彩彩票注册邀请码tephens, 杏彩彩票注册邀请码.杏彩彩票注册邀请码. 杏彩彩票注册邀请码omlin, 杏彩彩票注册邀请码.杏彩彩票注册邀请码. 杏彩彩票注册邀请码haw, 杏彩彩票注册邀请码.杏彩彩票注册邀请码. 杏彩彩票注册邀请码plett, 杏彩彩票注册邀请码. 杏彩彩票注册邀请码ayshenker, 杏彩彩票注册邀请码.杏彩彩票注册邀请码. 杏彩彩票注册邀请码hite, 杏彩彩票注册邀请码. 杏彩彩票注册邀请码ung, 杏彩彩票注册邀请码.杏彩彩票注册邀请码. 杏彩彩票注册邀请码ehman. 杏彩彩票注册邀请码eta-study of laser power calibrations ranging 20 orders of magnitude with traceability to the kilogram. 杏彩彩票注册邀请码etrologia.杏彩彩票注册邀请码 杏彩彩票注册邀请码ublished online 20 杏彩彩票注册邀请码ecember 2019. 杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码:

杏彩彩票注册邀请码eleased 杏彩彩票注册邀请码ecember 20, 2019
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