Scientists Successfully Measure Intensity Of World's Most Powerful Laser

Scientists are building extremely powerful lasers - in about a trillionth of a second, one of these machines emits thousands of times the power of the U.S. power grid.
Such devices could allow researchers to explore unsolved problems related to fundamental physical principles and develop innovative laser-based technologies.
But these applications require precise knowledge of the intensity of any such laser, a difficult parameter to measure because no known material can withstand the extreme conditions of the expected laser beam.
Now, Wendell Hill and his colleagues at the University of Maryland, Parker, have demonstrated a technique that uses electrons to determine this intensity.
In their demonstration, the researchers fired a high-power laser pulse at a low-density gas, causing the gas to release electrons. The laser's electromagnetic field then pushes these electrons forward and out of the laser beam. Using image plates that look like film, the team observed the angular distribution of the ejected electrons in real time.
By analyzing these image plates, Wendell Hill and his colleagues found that the angle of the emitted electrons relative to the direction of the beam was inversely proportional to the intensity of the laser, allowing this angle to be used as a benchmark for intensity measurements. The researchers demonstrated their method for laser intensities of 1019-1020 W/cm2 and suggested that it could be applied to an intensity range of 1018-1021 W/cm2. They claim that this method could help scientists field test the next generation of ultra-powerful lasers and study the interaction between matter and strong electromagnetic fields with high precision.