Figure 4. Continuous CARS spectra of toluene in the fingerprint region obtained by the rapid-scanning FT-CARS system.

Each CARS spectrum is obtained by segmenting and Fourier-transforming each interferogram in the time-domain waveform in Fig. 3. Consequently, the CARS spectrum is acquired at an ultrashort scan period of 41.7 μs/spectrum, corresponding to a scan rate of 24,000 spectra/s.