A researcher whose joint NIST work establishes quantitative photometry. A calibrated photometer relates its electrical output to illuminance, with corrections for its wavelength response and the spectrum of the source being measured. Those corrections matter because equal optical powers at different wavelengths need not appear equally bright to a human observer.[ref]
NIST Measurement Services: Photometric Calibrations by Yuqin Zong and others. §§3.2–3.5.6: photometer apparatus, readout and spectral-response corrections
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