Evaluation of illumination system uniformity for wide-field biomedical hyperspectral imaging
Evaluation of illumination system uniformity for wide-field biomedical hyperspectral imaging
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DOI：
10.1088/2040-8986/aa6176
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发表时间：
2017-04-01
影响因子：
2.1
通讯作者：
Bohndiek, Sarah E.
中科院分区：
文献类型：
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作者：
Sawyer, Travis W.;Luthman, A. Siri;Bohndiek, Sarah E.
高光谱成像（HSI）系统从样品中收集空间（形态学）和光谱（化学）信息。HSI可以为生物和医学应用提供灵敏的分析，例如，同时测量组织的反射率和荧光特性，这与结构信息一起可以改善早期癌症检测和肿瘤表征。照明均匀性是从HSI系统中提取定量数据的关键先决条件。不均匀性会导致眩光、镜面反射和不必要的阴影，这会对用于提取不同化学物质丰度的统计分析程序产生负面影响。在这里，我们模拟和评估几个照明系统经常用于宽场生物医学成像，以测试其潜在的HSI。我们使用软件LightTools和FRED。所分析的系统包括：光纤环灯;发光二极管（LED）环;和漫散射圆顶。每个系统的特点是光谱，空间和角度的均匀性，以及传输效率。此外，介绍了一种利用Kullback-Leibler散度（KLD）测量均匀性的方法。KLD是可推广到任意照明形状，使其成为一个有吸引力的方法来表征照明分布。虽然这些系统在空间和光谱均匀性方面具有相当的可比性，但使用漫散射圆顶实现了最均匀的角分布，在+/- 60（Ω）视场内产生了0.503的对比度和0.303的平均偏差，角域中的模型误差为3.9%。我们的研究结果表明，传统的照明源可以应用于HSI，但在低光水平的情况下，定制的照明源可以提供更好的性能。
Hyperspectral imaging (HSI) systems collect both spatial (morphological) and spectral (chemical) information from a sample. HSI can provide sensitive analysis for biological and medical applications, for example, simultaneously measuring reflectance and fluorescence properties of a tissue, which together with structural information could improve early cancer detection and tumour characterisation. Illumination uniformity is a critical pre-condition for quantitative data extraction from an HSI system. Non-uniformity can cause glare, specular reflection and unwanted shading, which negatively impact statistical analysis procedures used to extract abundance of different chemical species. Here, we model and evaluate several illumination systems frequently used in wide-field biomedical imaging to test their potential for HSI. We use the software LightTools and FRED. The analysed systems include: a fibre ring light; a light emitting diode (LED) ring; and a diffuse scattering dome. Each system is characterised for spectral, spatial, and angular uniformity, as well as transfer efficiency. Furthermore, an approach to measure uniformity using the Kullback-Leibler divergence (KLD) is introduced. The KLD is generalisable to arbitrary illumination shapes, making it an attractive approach for characterising illumination distributions. Although the systems are quite comparable in their spatial and spectral uniformity, the most uniform angular distribution is achieved using a diffuse scattering dome, yielding a contrast of 0.503 and average deviation of 0.303 over a +/- 60(omicron) field of view with a 3.9% model error in the angular domain. Our results suggest that conventional illumination sources can be applied in HSI, but in the case of low light levels, bespoke illumination sources may offer improved performance.