Fast active THz camera with range detection by frequency modulation

摘要

We report on the realization of two active fully electronic THz cameras operating at different frequencies (645 GHz and 300 GHz) and room temperature. Active illumination together with the frequency modulation continuous wave approach allows us to implement unique features, such as phase-sensitive detection, working-distance selection and the suppression of spurious reflections. With both systems we are able to acquire images with more than 50000 pixels (phase and amplitude) in 9 seconds. The dynamic range exceeds 35 dB and we achieve a sub wavelength depth resolution due to the measurement of the phase. The typical object distance is about 50-100 cm and the image size is on the order of hundreds of cm~2. With frequency modulation of the source we are furthermore able to detect the position form objects up to an accuracy of a few mm.