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RAP opportunity at National Institute of Standards and Technology     NIST

Radiation Pressure - Using the Momentum of Light to Measure its Power


Physical Measurement Laboratory, Applied Physics Division

opportunity location
50.68.62.B7583 Boulder, CO

NIST only participates in the February and August reviews.


name email phone
Paul A. Williams 303.497.3805


The momentum carried by light allows us to relate the optical power in a laser beam to the force it imparts when reflecting from a mirror. This presents several valuable measurement science opportunities. For example, the power in high power (CW) laser beams can be measured as a force without absorbing a significant fraction of the light. This greatly simplifies the measurement of laser power in the very high power regime (conventional thermal technologies must absorb all the light and are therefore heavy and slow). Even more intriguing is the fact that when radiation pressure is used to measure the power in a laser beam, that laser beam is reflected and still availiable to carry out its intented purpose (welding, cutting, or additive manufacturing, for example). Such simultaneous high accuracy power measurement during laser operation is not possible with traditional laser power metrology and has potential to improve quality of laser manufactured parts.

At a more fundamental level, we are working to explore the limits of the symbiotic relationship between optical power and force. For the highest power lasers, the measurement uncertainty can be improved with high accuracy force sensors. At low force values, force metrology can be improved with high accuracy measurments of laser power. We are currently working to reduce the uncertainty of laser power measurements by 10-100x through a radiation pressure measurement with passive optical force amplification.

We seek proposals for collaboration in all aspects of radition-pressure-based laser power metrology from single photon sensing to 100's of kilowatt power levels. Applications to both CW and pulsed sources are of interest. We are also interested in development of novel force sensing technologies dedicated to radiation pressure metrology. This could include improved force sensitivity, reduced noise floor or active isolation techniuqes. 

key words
Radiation pressure; High-power laser; Laser energy; CO2 lasers; Laser manufacturing; Laser welding; Laser cutting; Yb doped fiber laser; photon momentum; force sensing; laser radiometry;


Citizenship:  Open to U.S. citizens
Level:  Open to Postdoctoral applicants


Base Stipend Travel Allotment Supplementation
$82,764.00 $3,000.00
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