Fig. 4: Time-of-flight THz microscopic topography using GHOSTEAM.
a Structure of a prototype 3D object. The object with air grooves on SiO2 has three interfaces [indicated in yellow (upper), green (middle) and red (bottom)]. The arrow indicates the incidence direction of THz pulses with an illuminating area of FOV1. b Measured THz waveforms that passed through the sample within and outside the structured region. The solid dots indicate the EO sampling delay times of the TOF measurements with the GHOSTEAM system, corresponding to the three interfaces. Experimental subdiffraction-limited images in terms of height for the interfaces at 0 μm (c), 100 μm (d), and 200 μm (e). Note that experimental images were denoised using stationary wavelet transform (see “Materials and methods” for details). f–h, Simulated electrical distributions for the three interfaces relevant to c–e, respectively. The colour map for each image (c–h) is normalized individually.
