Based on tunable diode laser absorption spectroscopy (TDLAS), two-dimensional (2D) distribution reconstructions of gas concentration and temperature are realized using an algebraic reconstruction technique (ART). The influence of the beam distribution and grid size on combustion field reconstruction is investigated to attain optimal reconstruction results with a limited number of beams. Under limited optical-path numbers, it shows that a better spatial resolution is attainable only when the laser beam paths are vertical and parallel to the symmetry axis of the combustion field. Furthermore, experiments with 16 beam paths using one and two flat flame combustion fields are carried out in different fuel-air equivalence ratios under room temperature. The results are in agreement with the simulation results, and the time resolution is less than 1 s.

Temperature is an important physical quantity in most industrial processes. Distributed temperature sensor (DTS), fiber Bragg grating (FBG), and tunable diode laser absorption spectroscopy (TDLAS) are three primary techniques for temperature measurement using fiber optic sensing and spectrum technology. The DTS system can monitor space temperature field along the fiber in real time. In addition, it also can locate a fire source using two sections of optical fibers which are placed orthogonally to each other. The FBG temperature sensor is used to measure the point temperature. The temperature sensitivity of the bare FBG is 10.68 pm/°C and the linearity is 0.99954 in the range of 30–100°C. Based on tunable diode laser absorption spectroscopy (TDLAS), two-dimensional (2D) distribution reconstructions of gas temperature are realized using an algebraic reconstruction technique (ART). The results are in agreement with the simulation results, and the time resolution is less than 1 s.

A compact laser spectrometry instrument was developed for high precision measurements of isotope ratio of CO₂ by tunable diode laser absorption spectroscopy in the mid-infrared at 2.7 μm. The experimental spectrum of carbon isotopologues in the gas phase near 3641 cm⁻¹ is very suitable for real-time analysis of these isotopologues. Simultaneous measurements of the mixing ratio and the corresponding δ¹³C values of CO₂ in the atmosphere were performed. The achieved standard deviation (1σ) of δ¹³C was 1.8‰. The Allan analysis of the time series of the mixing ratio of CO₂ shows a measurement precision of 0.2‰ for δ¹³C with an optimum integration time of about 130 s. The spectrometer is capable of real-time measurements of stable carbon isotope ratios of CO₂ under ambient conditions.