Fig. 4: Performance evaluation of the time-stretch infrared (TS-IR) spectrometer.

a A non-averaged TS-IR spectrum of two molecular species, toluene and phenylacetylene. b A non-averaged TS-IR spectrum of narrow notch filters. The observed dips with single spectral points indicate that our TS-IR system has a spectral resolution determined by the spectral space between the adjacent spectral point, 15 nm (7.7 cm⁻¹), in this experiment. Errors of the spectral intensities in a, b are too small to be visible, which are evaluated by the standard deviation of the noise floor. c Linear concentration dependence of absorbance evaluated by the average of 30 absorbance spectra of phenylacetylene diluted in toluene. The unit V/V % indicates volume concentration. The error bars are evaluated by the standard deviation of 30 spectra. For the measurements of a, b, the average power of the optical parametric oscillator output was 55 mW.