Terahertz spectral imaging system and security surveillance system employing the same

Abstract

A terahertz (THz) spectral imaging system includes a THz 2D imaging camera, a tunable THz bandpass filter before the THz camera, and a broadband THz light source. The tunable THz bandpass filter includes a visible or infrared laser source, a spatial light modulator modulating the light to generate a spatially structured light pattern, and a semiconductor plate onto which the light pattern is projected. The light pattern generates carriers in the semiconductor plate to turn it into a metamaterial THz bandpass filter, which is tunable by changing the light patterns. A controller controls the light patterns and the THz camera in a timing sequence to acquire multiple 2D THz images at different THz frequencies. Such THz spectral image data can be further combined with visible images and LiDAR images in a security surveillance system to automatically detect security threats using image fusion and deep learning techniques.