Ronald Willey, Willey Optical, Consultants, Melbourne, FL
Calibrating transmittance is easy, stable, and reliable. Calibrating reflectance is much more vulnerable to errors. Reflectance attachments for spectrophotometers are reviewed and their pitfalls. Working standards for reflectance are described. Linearity calibration is discussed. Suggestions for the fabrication of a near-100% reflectance working standard are provided at length.