Synchrotron radiation-based irradiance calibration from 200 to 400 nm at the Synchrotron Ultraviolet Radiation Facility III

Abstract

A new facility for measuring irradiance in the UV was commissioned recently at the National Institute of Standards and Technology (NIST). The facility uses the calculable radiation from the Synchrotron Ultraviolet Radiation Facility as the primary standard. To measure the irradiance from a source under test, an integrating sphere spectrometer-detector system measures both the source under test and the synchrotron radiation sequentially, and the irradiance from the source under test can be determined. In particular, we discuss the calibration of deuterium lamps using this facility from 200 to 400 nm. This facility improves the current NIST UV irradiance scale to a relative measurement uncertainty of 1.2% (k=2).

Ultraviolet characterization of integrating spheres

“…One way to correct this effect for an integrating sphere and monochromator system is to treat the fluorescence as part of the monochromator line spread function. With the combined system completely characterized using a tunable laser, contributions from fluorescence and scattering can be mathematically alleviated from the output spectra by using a stray light reduction algorithm as was previously demonstrated [11]. While the absorption and fluorescence problems can be solved in principle, the issue of instability caused by contamination from both the laboratory and field environment is more difficult to resolve.…”

“…The spectral throughput of an integrating sphere was measured by utilizing part of a UV irradiance calibration system at the Facility for Irradiance Calibration Using Synchrotrons (FICUS) at NIST [10,11]. As shown in Fig.…”

“…The measured spectral distribution using the LIF setup with fixed wavelength laser excitation consists of fluorescence from the integrating sphere and the primary exciting laser line on top of two slowly decaying wings around the primary laser peak (i.e., line spread function) contributed by scattered stray light inside the spectrograph [11,13,14]. Shown in Fig.…”

“…In calibrating deuterium lamps at FICUS [11], we observed that an integrating sphere can have dramatic changes in its throughput over a few days. The cause of such a change was traced to diesel truck fumes leaking into the room where the measurement was performed.…”

A quarter‐century of metrology using synchrotron radiation by PTB in Berlin

“…Electron storage rings with calculable bending magnet radiation are currently used as primary source standards by the National Institute of Standards and Technology (NIST) at NIST's own facility SURF III in Gaithersburg (USA) [28] and by PTB, based on former work performed at BESSY I [29][30][31], at BESSY II [19,24] and the MLS [32,33]. At the latter two, PTB has installed and is operating equipment for the measurement of the storage ring parameters needed for the calculation of Φ λ according to Eq.…”