Today, near infrared ray(NIR) analysis is widely used to qualitative and quantitative analysis of unknown material which contains -CH,-OH,-NH, etc. With the aid of optical fiber, it can be applied not only to the laboratory experiment but also to the industrial on-line process monitoring. NIR spectrometer is composed of four main parts : light source, monochromator, test material, and sensor. As for light source, Tungsten-Halogen lamp is used because it illuminates continuous spectrum from UV to far IR. There are four kinds of mainly used monochromator: filter, grating, Fourier transform(FT), acousto-optic tunable filter(AOTF). Water was measured to verify the system performance.
The purpose of this paper is to acquire many different sample NIR spectrum with a single spectrometer. AOTF uses light diffraction by acoustic sinusoidal wave in the crystal. It can be easily controlled by electric signal and it has imaging capability. So it is suitable to acquire multipoint spectrum simultaneously. The principle of acousto-optics and design procedure of AOTF and its driver was summarized. And the AOTF and its driver was manufactured by Korea-China Cooperation Research. Three point optical fiber probe was designed to combine with AOTF.
Finally, after calibration of AOTF and its driver was conducted, water transmittance of this system and commercial spectrometer was compared to verify the system performance.
