Active remote sensing using a simultaneous spectral sampling technique

摘要

A material sensing system comprises a first optical radiation source tunable over a range of wavelengths; a second optical radiation source at a fixed reference wavelength; two modulators to modulate the two optical radiations at different frequencies to generate two different modulated optical radiations and a detector to detect both modulated optical radiations after interaction with sample and generate a detection signal. The system also includes two lock-in amplifiers to process the detection signal based on the first and second frequencies to produce two output signals.