Fig. 3: Time-stretch infrared (TS-IR) spectroscopy.
a Top figure shows the optical layout of the notch filter. A sharp 0.3-mm beam block is placed near the Fourier plane of the FACED system. Bottom figures show spectrally filtered TS-IR spectra. The dip in the waveform shifts by 13 nm in wavelength by shifting the position of the beam block by 0.5 mm in the Fourier plane, which agrees well to the theoretical estimation. The gray lines show the positions of the beam block (notch filter). b Continuously measured molecular absorption TS-IR spectra of phenylacetylene at a rate of 80 MHz (12.5 ns interval between the adjacent spectra). c A magnified spectrum of b. An absorption line of the C–C triple bond is clearly observed. d A reference absorption spectrum of phenylacetylene measured by Fourier-transform spectroscopy.
