The measurement of particle size distribution (PSD) in colloids and nanofluids presents many challenges, especially when it requires to be conducted in-situ and real-time. Our work aims to assess the capabilities of Light Extinction Spectroscopy (LES) technique to determine concentration and volumetric PSD (vPSD) of colloids and nanofluids. Numerical simulations are performed to verify robustness of LES data inversion algorithm and to identify the most relevant uncertainty sources. Experiments are carried out on well-dispersed water based colloids containing Polystyrene particles with median diameters at 120 nm and 300 nm. LES results are compared with supplier’s data, 3D-DLS measurements, and SEM images. Via sensitivity analyses, LES sensitivity to particle complex refractive index spectrum and to system noise level are examined. To improve accuracy, we limit LES data inversion at shorter wavelengths where high SNR is acquired. The noise is experimentally characterized and embedded into numerical simulations to better mimic the real conditions. We show that while noise level affects mostly vPSDs’ peak height, small inaccuracies in complex refractive index spectrum deteriorate the stability of the inversion, especially for smaller vPSDs. To overcome the latter, we carry out a preliminary in-situ calibration on particle complex refractive index spectrum. Accordingly, results are substantially improved with maximal discrepancies smaller than 3% for median and volume mean diameters, and lower than 13% for number concentrations. Besides, the retrieval of bi-modal distribution is promising. In conclusion, our methodology can be considered as a guideline to evaluate the applicability and accuracy of the LES technique in colloids.

胶体和纳米流体中粒度分布（PSD）的测量提出了许多挑战，尤其是当它需要在原位和实时进行时。我们的工作旨在评估消光光谱（LES）技术确定胶体和纳米流体的浓度和体积PSD（vPSD）的能力。进行数值模拟以验证LES数据反演算法的鲁棒性，并确定最相关的不确定性来源。对分散良好的水基胶体进行实验，该胶体包含中值直径为120 nm和300 nm的聚苯乙烯颗粒。将LES结果与供应商的数据，3D-DLS测量结果和SEM图像进行比较。通过灵敏度分析，检查了LES对粒子复数折射率谱和系统噪声水平的灵敏度。为了提高准确性，我们将LES数据反演限制在获取高SNR的较短波长处。对噪声进行了实验表征，并嵌入到数值模拟中以更好地模拟实际条件。我们表明，虽然噪声水平主要影响vPSDs的峰高，但复杂折射率谱中的小误差会降低反演的稳定性，尤其是对于较小的vPSDs。为了克服后者，我们对粒子复数折射率光谱进行了初步的原位校准。因此，结果显着改善，最大偏差小于中值和体积平均直径小于3％，小于数字浓度小于13％。此外，双峰分布的检索是有前途的。结论，