Development of an absorption-corrected method for 3D computed tomography of chemiluminescence

The computed tomography of chemiluminescence (CTC) technique is an advanced volumetric imaging technique that can resolve the internal structure of a flame and has found extensive applications in spatiotemporally resolved measurements of complex combustion phenomena. Despite its extensive application, certain improvements are still long-desired to further enhance its performance and reduce measurement uncertainties. Based on the Beer-Lambert law, this work introduces absorption correction into the CTC technique to account for the impact of signal attenuation in the tomographic algorithm. A reverse ray tracing method with distortion correction is proposed to calculate the absorption length within each cubic voxel and the corresponding absorption term, which has been ignored by previous works. To mathematically resolve the coupling process between chemiluminescence attenuation and accumulation during the signal trapping, an alternating-iteration reconstruction algorithm is developed. The results from a proof-of-concept experiment prove the good fidelity of the absorption-corrected CTC technique in solving the 3D distribution of chemiluminescence.