Quasi-optic synthetic phased-array terahertz imaging

摘要

A quasi-optic terahertz (THz) imaging system that utilizes optoelectronic methods for pulsed THz generation and reception and optical methods for image formation is demonstrated and theoretically explained. The system can be used to produce coherent, field amplitude, and energy density images with diffraction-limited resolution in two transverse dimensions. Simultaneous bandwidth-limited resolution is achieved in the depth dimension by means of the ranging capabilities of the system. The system is shown to accurately produce images of several objects to verify diffraction-limited imaging. Imaging power is extended by aperture synthesis to result in transverse resolution the order of a wavelength. Several individual, coherent images are recorded, each synthetically appearing to be formed by a different element of an optical phased array. The multiple images are simply superposed to create a higher-resolution image. Theoretical calculations fully describe the broadband imaging and include aberration and diffraction effects to further verify system performance. Calculated images are a good match with experimental results. (C) 2004 Optical Society of America.