Enabling Ground Based Materials Analysis and Identification Using Reflectance Spectroscopy

This paper discusses radiance and wavelength calibration methods for field portable spectroradiometers and presents typical protocols for deriving spectroradiometer signal to noise ratio (SNR) for measurements performed in the lab as well using solar illumination. The paper presents how the selection of the light source and its irradiance, or the signal, affects the SNR measurement, a quantity often used to compare spectroradiometers. This paper will also present a method to determine noise equivalent spectral radiance, or NEdL, or a quantity proportional with the noise experienced by the user, and why it determines spectroradiometer performance in the field. Paper will also discuss the impact of spectral resolution on reflectance measurements between 350 and 2,500 nm. We will also discuss factors affecting spectrometer resolution function and how fixed array spectrometers differ from rotating grating spectrometers. Finally, we will discuss how improved resolution in the visible to near infrared (VNIR) region of the spectrum is important in resolving spectral features of rare earth minerals.