Polarization-resolved terahertz time-domain imaging enabled by single pixel imaging

This work presents an efficient far-field single pixel imaging (SPI) system adapted to broadband, pulsed terahertz (THz) detection to successfully reconstruct polarization-resolved hyperspectral THz images of a polarizing sample of varying thickness. Polarizing S-cyclic Hadamard masks are used to efficiently encode the pulsed imaging beam polarization prior to interaction with the sample. In the reconstructed images, 320-ps-duration THz pulses are reconstructed for each spatial pixel. The corresponding hyperspectral THz images are then examined at frequencies between 0.10 and 1.00 THz with a frequency resolution of 3 GHz. A 17 × 19 three-dimensional image is presented to summarize the amplitude and phase of the reconstructed hyperspectral THz images in order to measure the refractive index and extinction coefficient of the sample polymethyl methacrylate material. Diffractive effects relating imaging wavelength and SPI mask pixel dimension are explored, in which diffraction broadening is significant for pixel sizes less than 1.2 wavelengths. This work has the potential to be the basis for future polarization-resolved THz imagers, particularly for those utilizing a single detector.