Principles of terahertz(THz) interferometric synthetic aperture imaging with heterodyne and optical techniques are presented.A THz interferometric experiment based on optical up-conversion is set up.The received THz signal is modulated into an optical carrier and transmitted in a fiber.To simulate phase differences between two THz receivers,the output of receiver is divided and a phase shifter is placed before electro-optical modulation(EOM).Interferometric spectra of these modulated optical signals are examined at different phase shifts.Otherwise,carrier suppression and phase error calibration are discussed for THz interferometric synthetic aperture imaging.