Realistic ports in integrating spheres: reflectance, transmittance, and angular redirection

Tang Chhayly; Meyer Matthias; Darby Brendan L.; Auguie Baptiste; Le Ru Eric C.

摘要

We use Monte Carlo ray-tracing modeling to follow the stochastic trajectories of rays entering a cylindrical port from inside an integrating sphere. This allows us to study and quantify properties of realistic ports of non-negligible length, as opposed to the common thin-port assumption used in most theoretical treatments, where the port is simply considered as a hole in the spherical wall. We show that most practical ports encountered in integrating sphere applications cannot be modeled as thin ports. Indeed, a substantial proportion of rays entering the port can be reflected back into the sphere, with port reflectances as high as 80% demonstrated on realistic examples. This can have significant consequences on estimates of the sphere multiplier and therefore pathlength inside the sphere, a critical parameter in many applications. Moreover, a nonzero port reflectance is inevitably associated with reduced transmittance through the port, with implications in terms of overall throughput. We also discuss angular redistribution effects in a realistic port and the consequences in terms of detected throughput within a fixed numerical aperture. Those results highlight the importance of real port effects for any quantitative predictions of optical systems using integrating spheres. We believe that those effects can be exploited to engineer ports for specific applications and improve the overall sphere performance in terms of pathlength or throughput. This work carries important implications in our theoretical understanding of integrating spheres and on the practical design of optical systems using them. (C) 2018 Optical Society of America

机译：我们使用Monte Carlo射线跟踪模型来遵循从整合球内进入圆柱端口的光线随机轨迹。这使我们能够研究和量化不可忽略的长度的现实港口的特性，而不是大多数理论处理中使用的常见薄端口假设，其中端口被认为是球形墙壁中的孔。我们表明，在集成在集成的球体应用中遇到的大多数实用端口不能被建模为薄端口。实际上，进入端口的大部分光线可以反射回球体，端口反射高达80％在现实例子上证明。这对球体乘法器的估计和因此球体内部的路径长度来说，这可能具有重大影响，许多应用中的关键参数。此外，非零端口反射率不可避免地通过端口减少透射率，这在整个吞吐量方面具有含义。我们还讨论了在固定数值孔径内检测到的吞吐量方面的角度再分配效果。这些结果突出了使用集成球体的光学系统的任何定量预测的真实端口效应的重要性。我们认为，这些效果可用于特定应用程序的工程端口，并在路径长度或吞吐量方面提高整体球体性能。这项工作对我们对整合领域的理论理解和使用它们的光学系统的实际设计进行了重要意义。（c）2018年光学学会

Realistic ports in integrating spheres: reflectance, transmittance, and angular redirection

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