Spectrophotometers or optical benches using integrating spheres to measure normal-hemispherical transmittance are widespread laboratory equipments. Although it is known that they cannot be used for ”highly turbid” samples, because multiple scattering may lead transmitted radiation to miss the entrance of the integrating sphere, very little is generally known about their exact validity range. Here we present a method to characterize the validity range of such spectrophotometer and observe that most of them fail to measure for scattering optical thickness above 0.25 ( for in the case of non absorbing media with ). We also show how it is possible to continue using spectrophotometers even outside their measurement validity range, without any calibration, thanks to a proper simulation of radiative transfer and geometrical optics. We make available the corresponding radiative transfer simulation tools as open access codes, that have been developed for a straightforward implementation on a wide range of experimental setups. The method is validated on three different spectrophotometers or optical benches using standardized latex microspheres, then its practical implementation is illustrated in the case of semi-conductor particles and photosynthetic microalgae. Errors in analysis arising from the misuse of such optical devices are discussed throughout the article.

中文翻译：

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通过建模 3D 多重散射辐射传输来扩展正常半球透射率（[公式省略]）测量的使用


使用积分球测量法向半球透射率的分光光度计或光具座是广泛使用的实验室设备。尽管众所周知它们不能用于“高度混浊”的样品，因为多次散射可能导致透射辐射错过积分球的入口，但人们对其确切的有效范围知之甚少。在这里，我们提出了一种方法来表征此类分光光度计的有效范围，并观察到大多数分光光度计无法测量高于 0.25 的散射光学厚度（对于具有 的非吸收介质的情况）。我们还展示了如何通过对辐射传输和几何光学的适当模拟，即使在测量有效范围之外也可以继续使用分光光度计，而无需任何校准。我们提供相应的辐射传输模拟工具作为开放访问代码，这些工具是为了在各种实验设置上直接实施而开发的。该方法使用标准化乳胶微球在三种不同的分光光度计或光具座上进行了验证，然后在半导体颗粒和光合微藻的情况下说明了其实际实施。整篇文章都讨论了因滥用此类光学设备而产生的分析错误。