Table 3.

Summary of the different optical techniques described in Section 2.1.

Technique	Spectral Range cm−1	Molecule	Measurement Time	Frequency Accuracy (cm−1)	Optical Power/Wavelength	Cost	Refs
FT-IR	1020–1510	dioxins and furans	<60 s	0.9	<1 µW	Low	[19]
ECDL-QCL	1205–1310 And 1335–1590	dioxins and furans	4 min (first range); 14 min (second range)	0.1	Tens/hundreds of mW	Medium	[18]
Rapid scan QCL	860–1100	ethylene, propene, 1-butene, 2-butene, 1,3-butadiene, methanol	down to 3 ms	0.35	≤1 W	High	[56]
Dual Comb based IR spectrometer	1180–1250	Protein in Halobacterium salinarum	1 µs	0.3 *	Typically between 1 µW and 1 mW	High	[72]

* The target of this paper was fast reaction, so for different experiments the accuracy could reach the order of 3 × 10⁻⁴ cm⁻¹ (10 MHz).