| Popis: |
We propose an opto-electronic THz vector imaging system based on a self-mixing detection receiver, which can be used to measure thickness of samples. In the proposed system architecture, a THz signal is generated by microwave photonics technology and received by a Schottky barrier diode detector. In the THz free space transmission link, four parabolic mirrors are used to collimate the THz signals, and the sample under test is placed at the focal point of a parabolic mirror. At the receiver side, the transmission signal is down-converted by Schottky barrier diode detector, and the phase information is acquired by a lock-in amplifier, which is used for sample imaging and thickness detection. In the experiment demonstration, a Mach-Zehnder modulator with carrier-suppression is used to generate a two-tone optical signal, and coupled with an external cavity laser for photomixing generation of a two-tone THz signal in the 300GHz frequency band at an uni-traveling carrier photodiode. Several samples with different thicknesses are imaged and compared in the experiment, and the measured thickness error is estimated to be about 3.84%. |
