Multipoint Process Monitoring System Based on a Near Infrared Ray(NIR) Acousto-Optic Tunable Filter(AOTF)

This paper describes a newly designed multipoint process monitoring system based on a NIR acousto-optic tunable filter. The NIR multipoint process monitoring system consists of a NIR AOTF device for wavelength selection, an InGaAs array sensor, and a specially designed iin-line type of optical fiber probe. Unlike a FTS(Fourier Transform Spectrometry) or grating based monitoring system, an AOTF has no moving parts, and it can be rapidly tuned to any wavelength in its operating range within microseconds. Thus, the AOTF is advantageous in terms of faster spectral imaging capability and rigidity required for industrial monitoring environment. In the current feasibility evaluation, an enhanced optical fiber probe with 3 monitoring points was used. However, ...