Available Technology

Radiation Pressure Power Meter

Lasers play many roles in manufacturing processes. To control these tasks, manufacturers must ensure that their lasers fire at the correct power. However, to date there has been no way to precisely measure laser power during a manufacturing process. The current practice is to use an external optical meter to measure laser output during testing, but NOT during the manufacturing process. The most fundamental method for checking the performance of a laser is to measure its power or energy output. Conventional techniques for gauging laser power require an apparatus that absorbs all the energy from the beam as heat. Measuring the temperature change allows researchers to calculate the laser's power.The problem with this approach however, is that you cannot use the laser while measuring performance. Without this information some manufacturers may have to spend more time and money assessing whether their parts meet manufacturing specifications after production.

This patent presents an alternative for measuring performance based on heat, instead measuring performance based on radiation pressure. NIST provides the RPPM as a Standard Reference Instrument which is available for purchase. Possible markets include 3D printing and welding. Other potential applications include directed energy weapons and robotic lasers used in the production of automobiles.

Abstract: 

An optical meter includes a force member to receive a force and a reflector disposed on the force member to receive radiation and to communicate a pressure of the radiation to the force member. The reflector includes a reflective surface, and the force member is configured to be displaced in response to receiving the force comprising the pressure. The optical meter is configured to measure a power of the radiation, an energy of the radiation, or a combination thereof based on the pressure. A process for measuring a property of radiation includes receiving radiation by the reflector, reflecting radiation from the reflective surface, communicating a pressure from the reflector to the force member, and displacing the force member.

Benefits: 

Unlike the traditional heat sink power meters, the NIST optical meter makes its measurements in real time: After the light hits the balance, it can be used directly for applications such as cutting and welding. This patent covers a wide range of power including power greater than or equal to 100 Kilowatts (kW), as well as power from 1 mW to 200kW.

Inventors: 

John Lehman, Paul Williams, Robert Lee, and Frank Maring

Patent Number: 
9625313
Technology Type(s): 
Homeland Security, Laser and Optics, Laser Applications, Advanced Manufacturing Processes, Optical Radiation, and Precision Measurement
Internal Laboratory Ref #: 
13-018
Patent Issue Date: 
April 18, 2019
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