Accuracy improvement

Measurements of the intensity of light at different wavelengths can be made more accurately now, thanks to a new, simple method for correcting common instrument errors. The new method, developed by researchers at the National Institute of Standards and Technology (NIST), will benefit fields such as colour measurement, lighting development, remote sensing, biotechnology and astronomy.

The NIST method improves the measurement accuracy of spectrometers, devices that measure optical radiation at different wavelengths. Spectrometers are used widely in industrial settings and academic research to analyze the emissions from lamps or other light sources, as well as to analyze optical properties of materials. The NIST method corrects errors arising from the presence of stray light, unwanted scattered radiation within an instrument.

Stray light is often the major source of measurement uncertainty for commonly used spectrometers. It can cause unexpectedly large systematic errors, even as much as 100 percent depending upon the application, when an instrument tries to measure a very low level of radiation at some wavelength while there are relatively high levels in other wavelength regions. The new NIST method nearly eliminates stray light errors, to a level less than 0.001 percent of the total signal, a desirable level for most industrial and scientific applications. This allows very accurate measurement of low-power components of radiation and accurate measurements across a large dynamic range of intensities.