Technique for designing NIR instrument to Acquire and Process Weak Signal

摘要

Acquiring useful signal from large noises is a crucial consideration during NIR instrument design. In the paper, the characters of signal and noise in NIR instrument are analyzed and light signal acquiring and disposing process is researched. A practical circuit used in the near infrared diffuse reflection instrument is introduced, and every process in the light signal acquiring and processing is analyzed according to the practical circuit. Besides, some other problems such as the choice of the fittest work frequency are discussed too. The conclusion is that modulating the light signal with optical chopper is an effective method to inhibit the noise, and phase sensitivity detection technique can effectively acquire signals emerged in the noise.