Synchrotron Improves Calibrations

The upgraded synchrotron ultraviolet radiation facility, known as Surf III, at the National Institute of Standards and Technology (NIST) in Gaithersburg, Md., is producing radiation with greater accuracy, purity and power than its predecessor, which was the national radiation standard from 1974 to 1998. NIST said the improved facility's 13 beam lines will benefit a range of photonic applications, from the production of mirrors for semiconductor photolithography to the calibration of satellite-borne environmental sensors.

Surf III uses a magnetic torus to precisely accelerate a stream of electrons, which gives the particles the energy to emit photons at specific wavelengths from the infrared to x-rays. Improvements in the generation and control systems of the magnetic field have reduced variations in the acceleration a hundredfold and lessened the uncertainty of irradiance measurements.