Precise and large-dynamic-range surface profilometry using time-of-flight detection of femtosecond optical pulses

Abstract

We demonstrate a new precise TOF detection-based surface profilometry technique by utilizing FLOM-PD's sub-fs resolution electro-optic sampling between an optical pulse train and a microwave signal. The imaging can be realized by scanning the sample's position laterally, as a scanning LIDAR system does. Using this technique, three samples of different step heights are successfully imaged. Our method achieves high precision of 4.2 nm repeatability and large maximum detectable range of 9.1 mm NAR, and accordingly, dynamic range is larger than 120 dB.