Distance displacement measurement with two-photon absorption process in Si-APD and high-speed optical millimeter wave scanner

A high-speed optical millimeter wave scanner has been developed and introduced into the distance displacement measurement based on two-photon absorption (TPA) process in a Si-APD. The TPA-based distance displacement measurement can measure the displacement of an object at 10 mm to 10 km away in principle. The measurement for the long distance of 10 m to 10 km was already realized by using intensity modulated light with a modulation frequency range of 10 GHz in the last study. The high-speed optical millimeter wave scanner developed in this study scanned over 100 GHz in 10 ms at its highest speed. We have successfully measured the short distance of 10 mm with a data acquisition time of 1 s and an accuracy of 6.34×10-3 .