Author: Michaela Kastanek, ASD Chemometric Specialist
In the world of NIR spectroscopy the words “calibration”, “white reference”, and “baseline” are often used interchangeably. Essentially these are all describing the same thing – the use of a reference material that has essentially 100% reflectance to calibrate the instrument to create a reflectance spectrum. But that raises a few questions. What is this white reference? Why is it needed? And is it truly 100% reflective?
What is it?
ASD field and lab based spectrometers all use a sintered polytetrafluoroethylene material better known by its commercial name, Spectralon, as a white reference. Produced by LabSphere and sold with all ASD instruments, Spectralon has a few unique qualities that make it an ideal material for optimizing ASD spectrometers. It comes in large and small round disks and square flat panels. It is rugged enough for field work and relatively easy to clean, and it is thermally and chemically stable.