A measurement method in near infrared spectroscopy for reference correction with the homologous optical beams

Abstract

In order to improve the stability of the portable near infrared (NIR) spectrometer, a measurement method in NIR spectroscopy (e.g. reference correction with the homologous optical beam) was proposed. Based on the measurement method, the contrast sampling mechanism was designed to obtain the reference beam from light source to ensure that the reference beam and the light source drift in the same trend. The reference beam can be used to eliminate the drift of the measured spectral data due to the drift of the light source. Then, by using the contrast sampling mechanism, the NIR spectrometer for reference correction with the homologous optical beams was developed. Using the newly designed spectrometer, the experiment to compare the performance of the single optical path detection method and dual optical path detection method was conducted. According to experimental results, the stability of the newly designed spectrometer achieved substantial improvement. The baseline drift of the reflectance spectra of gilding aluminium plate was decreased from 0.37% (with single optical path detection) to 0.074%, while the baseline drift of the reflectance spectra of kaolin was decreased from 2.92% to 0.16%.