This spectral reflectance can be also measured using a spectrophotometer or a spectral reflectometer, or may be measured using the densitometer for measuring {HEAD ~ the optical density} as {TAIL ~ a logarithm} of the spectral reflectance 
as
This spectral reflectance can be also measured using a spectrophotometer or a spectral reflectometer , or may be measured using the densitometer for measuring { HEAD ~ the optical density } as { TAIL ~ a logarithm } of the spectral reflectance
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH