Fluorescent strip-lights as a source of error in tissue reflectance spectroscopy

Tissue reflectance spectroscopy is a widely used technique for measuring the blood content of the skin. Fluorescent strip-lighting of a type in widespread use (Osram L36 W/23 Gelbweiss-white) is a potential source of misleading artefacts in tissue reflectance spectroscopy. The fluorescent light signal has successive peaks and troughs in the 520-580 nm range which closely emulate the inverse of the reflected signal of white light modulated by blood. The presence of fluorescent light in the reflected signal cancels some of the blood signature. Conversely, the presence of fluorescent light in the white reference augments the true blood reflected signal. The marked similarity of the resultant artefact blood spectrum to the true blood spectrum is a hazard, as the presence of the artefact may go undetected.