Forward modeling of inherent optical properties from flow cytometry estimates of particle size and refractive index
Forward modeling of inherent optical properties from flow cytometry estimates of particle size and refractive index
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DOI：
10.1364/ao.57.001777
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发表时间：
2018-03-10
期刊：
影响因子：
1.9
通讯作者：
McKee, David
中科院分区：
文献类型：
--
作者：
Agagliate, Jacopo;Lefering, Ina;McKee, David
开发了一种基于mie的正演建模程序，从先前开发的流式细胞术（FC）方法获得的粒度分布（psd）和真实折射率分布（PRIDs）中重建体固有光学特性（IOPs）。光学学报，57,1705(2018)]。考虑到可用的psd、该方法检测范围外粒子分数的外推以及复折射率输入(实部n（r)直接估计，虚部n(i)分别改编自有机和无机组分的文献），该模型产生体积散射函数，将其集成以产生散射和后向散射系数，以及用于计算吸收系数的吸收效率。该方法应用于从英国沿海水域采集的天然样品中提取的psd和prid，并使用CytoSense流式细胞仪（CytoBuoy b.v.，荷兰）进行分析。利用ac-9分光光度计和BB9后向散射仪（WET Labs Inc.， OR）在同一水域测量的原位IOPs和重建IOPs之间进行了光学闭合分析。结果表明，该方法与颗粒散射（b(p)）和后向散射（b(bp)）[均方根百分比误差（RMS%E）分别为35.3%和44.5%]和后向散射比（b(bp)） （RMS%E: 77%）大致一致。然而，该方法通常高估了颗粒吸收（a(p)） （RMS%E: 202.3%）。这种封闭程度取决于将最近开发的散射误差修正应用于吸收和衰减的原位测量。这些结果不仅间接验证了FC方法作为测定自然粒子群PSD和PRID的有用工具，而且还表明Mie理论可能是测定大量IOP的一个足够的模型，之前报道的困难可能是由于IOP测量不充分校正造成的。最后，在FC方法的一个独特功能中，同时检索尺寸和折射率可以评估颗粒群的有机与无机，荧光与非荧光部分对IOPs的相对贡献，并确定哪些尺寸类别对这些属性的影响最大。(C) 2018年美国光学学会
A Mie-based forward modeling procedure was developed to reconstruct bulk inherent optical properties (IOPs) from particle size distributions (PSDs) and real refractive index distributions (PRIDs) obtained using a previously developed flow cytometric (FC) method [Appl. Opt. 57, 1705 (2018)]. Given the available PSDs, extrapolations for the particle fraction outside the detection limits of the method and a complex refractive index input (with real part n(r) directly estimated and imaginary part n(i) adapted from the literature separately for organic and inorganic components), the model produces volume scattering functions that are integrated to produce scattering and back-scattering coefficients, and absorption efficiencies that are used to calculate absorption coefficients. The procedure was applied to PSDs and PRIDs derived from natural samples retrieved in UK coastal waters and analyzed using a CytoSense flow cytometer (CytoBuoy b.v., The Netherlands). Optical closure analysis was carried out between reconstructed IOPs and in situ IOPs measured using an ac-9 spectrophotometer and a BB9 backscattering meter (WET Labs Inc., OR) in the same waters. The procedure is shown to achieve broad agreement with particulate scattering (b(p)) and backscattering (b(bp)) [root mean square percentage error (RMS%E): 35.3% and 44.5%, respectively) and to a lesser degree with backscattering ratio (b(bp)) (RMS%E: 77%). The procedure, however, generally overestimated particulate absorption (a(p)) (RMS%E: 202.3%). This degree of closure was dependent on applying recently developed scattering error corrections to both absorption and attenuation in situ measurements. Not only do these results indirectly validate the FC method as a useful tool for PSD and PRID determination in natural particle populations, they also suggest that Mie theory may be a sufficient model for bulk IOP determination, with previously reported difficulties potentially being caused by inadequately corrected IOP measurements. Finally, in a feature unique to the FC method, the concurrent size and refractive index retrieval enabled assessment of the relative contributions that organic versus inorganic, fluorescent versus non-fluorescent fractions of the particle populations had on the IOPs, and identified which size classes had the largest influence on each of these properties. (C) 2018 Optical Society of America