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Beamline 4: Ultraviolet Optical Properties and Calibrations


Beamline 4 is a general purpose radiometric beamline consists of a 2 m normal-incidence monochromator to disperse radiation from SURF III. An Absolute Cryogenic Radiometer (ACR) at the end of the beamline accurately determines the radiant flux of the dispersed beam which, in turn, is used to calibrate the response of photodetectors. We have achieved an uncertainty of less than 1% (k=2) from 135 nm to 325 nm in measuring the spectral response of a typical silicon detector. In addition to detector power response calibration, the flexible design of the beamline enables a wide range of measurements such as reflectivity, internal quantum efficient, irradiance responsivity and radiation degradation of photodetectors as well as reflectivity and transmission of optical materials. Such studies allow us to understand and model the behavior of various solid-state photodetectors and have a great impact on accurate UV detection for industries such as UV curing and semiconductor photolithography.

The beamline is currently undergoing refurbishment. The CaF2 window between the monochromator and the end station has been replaced by a MgF2 window, which should extend the usable wavelength range down to about 115 nm.

Specifications / Capabilities:

  • Normal incidence wavelength range: 140 nm to 320 nm (now 115 nm to 320 nm)
  • Absolute cryogenic radiometer (ACR) based radiometric beamline
  • UV detector calibrations
  • Detector radiation damage studies
  • Optical properties of UV materials
  • Combined relative uncertainty < 0.5 %
ACR Beamline 4 SURF
Beamline 4 end-station with the absolute cryogenic radiometer.

Name: Uwe Arp
Phone: 301-975-3233
Email: uwe.arp@nist.gov
100 Bureau Dr, MS 8411
Gaithersburg, MD 20899-8411

Name: Ping-Shine Shaw
Phone: 301-975-4416
Email: ping-shine.shaw@nist.gov