Table 4 Comparison of mid-IR laser solutions for rapid acquisition of spectra, showing different combinations of wavelength range, acquisition frequency and linewidth.
Laser type | Wavelength coverage | Scan frequency/kHz | Scan speed/cm−1/s | Linewidth/resolution (typical) | Reference |
|---|---|---|---|---|---|
EC-QCL, pulsed | 1370 to 1850 cm−1 (or wider) | Not stated | 2.5 × 104 | 2 cm−1 | Block Engineering Lasertune35 |
EC-QCL, pulsed | 4–13 μm | Not stated | 5 × 103 | 1 cm−1 | Daylight Solutions Hedgehog36 |
EC-QCL, CW | 30 cm−1 mode-hop free | Not stated | 5 × 103 | 100 MHz (0.003 cm−1) | Daylight Solutions Hedgehog36 |
EC-QCL, square-wave modulated | 1520 to 1625 cm−1 | 200 Hz | 2 × 104 | 0.2 cm−1 | Brumfield et al.37 |
EC-QCL with rotating polygon mirror | 1520 to 1625 cm−1 | 4 kHz | 4.2 × 105 | 0.05 cm−1, mode spacing 0.5 cm−1 | Revin et al.38 |
EC-QCL | 7cm−1 at 992 cm−1 | 1 kHz | 7 × 103 | 0.38 cm−1 | Tsai and Wysocki39 |
EC-QCL, pulsed | 1090 to 1390 cm−1 | 6 kHz | 1.8 × 106 | 1 cm−1 | Hugger et al.40 |
EC-QCL, CW | 2105 to 2240 cm−1 | 100 Hz | 13.5 × 103 | 0.2 cm−1 | Jia et al.41 |
EC-QCL, CW with AOM | 1070 to 1135 cm−1 | 62.5 kHz | 4.1 × 106 | 1.5 cm−1 | Lyakh et al.42 |
EC-QCL, quasi-CW with AOM | 1020 to 1170 cm−1 | 62.5 kHz | 9.4 × 106 | 4.7 cm−1 | Lyakh et al.42 |
