Fig. 1. (a) Schematic diagram of transmissive terahertz time-domain spectroscopy. HWP: half-wave plate, PBS: polarization splitting prism, L: lens, PM: parabolic mirror, QWP: quarter wave plate, and P: polarizer; (b) Experimental tablet sample and corresponding molecular formula

Fig. 2. (a) Time domain signal and (b) frequency domain spectrum of the THz-TDS

Fig. 3. Transmittances of (R)-(-)-ibuprofen and (S)-(+) -ibuprofen for linear polarized terahertz wave. (a) Transmittances of (R)-(-)-Ibuprofen for same linear polarization; (b) Transmittances of (R)-(-)-Ibuprofen for cross linear polarization; (c) Transmittances of (S)-(+)-Ibuprofen for same linear polarization; (d) Transmittance of (S)-(+)-Ibuprofen for cross linear polarization

Fig. 4. Transmittances of (R)-(-)-Ibuprofen and (S)-(+) -ibuprofen for circular polarized wave. (a) Transmittances of (R)-(-)-Ibuprofen for same circular polarization; (b) Transmittance of (R)-(-)-Ibuprofen for cross circular polarization; (c) Transmittance of (S)-(+)-Ibuprofen for same circular polarization; (d) Transmittance of (S)-(+)-Ibuprofen for cross circular polarization

Fig. 5. Terahertz CD spectra of (R)-(-)-Ibuprofen and (S)-(+)-ibuprofen