Available Technology

Non-Inertial Photon Momentum Sensor

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. Without this information, some manufacturers may have to spend more time and money assessing whether their parts meet manufacturing specifications AFTER production.

The challenge addressed with the "photon momentum sensor", more commonly called the smart mirror, is to create a compact laser power sensor that could be included in the laser head and potentially be used in fast inline process monitoring. It is a radiation-pressure power meter (RPPM) that employs a dual spring detector concept. Two identical springs are used in a tandem configuration that mitigates environmental vibration signals, as well as errors due to changes in the sensor tilt. This method improves both sensitivity and speed (250 times faster than RPPM) and makes it a strong candidate for use in applications requiring a small compact sensor.

The smart mirror, provides new opportunities for manufacturers of lasers used in additive manufacturing (interchangeably known as 3D printing) and welding which require low-beam intensity in the mid-range. This approach allows the sensor to be embedded at the end of a robotic arm or in additive manufacturing and laser welding systems where the laser head will move and rotate. The size and reliability of this device enables it to be incorporated within the laser itself and measure performance while the laser is being used. This will help accelerate the parts qualification process.

Possible markets include additive manufacturing and laser welding applications that require low beam intensity in the mid-range. Sample applications include the production of medical devices, dentistry and aerospace applications. Established markets that use additive manufacturing in medical technology, dental, and aerospace applications are robust and expanding globally. Welding applications also are a potential target.

Patent Abstract: 

Radiation pressure is a force that results when light reflects from a mirror. By measuring the force on a mirror, the power in a laser beam can be assessed. We have invented a miniaturized mirrored force sensor that combines several key elements to make a sensor that is smaller, faster, more sensitive to force and less sensitive to noise, gravity, and thermal effects.


The compact size and consistent performance of the “smart mirror” within lasers that require low-beam intensity in the mid-range makes this compelling. The device can be readily built into additive manufacturing and welding devices to provide real-time measurements, rather than having to perform measurements off-line.


Alexandra Artusio-Glimpse, John Lehman, Michelle Stephens, Nathan Tomlin, Paul Williams, and Ivan Ryger

Patent Number: 
Technology Type(s): 
Laser Application, Laser and Optics, Advanced Manufacturing Processes, Health Care, and Precision Measurement
Internal Laboratory Ref #: 
Patent Issue Date: 
March 19, 2019
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