基于光纤光谱仪测量茶叶表面颜色的研究

Tea color measurement with fiber spectrometer

茶叶表面颜色是评定茶叶质量优劣的重要指标,介绍了一种基于光纤光谱仪测量一定范围内茶叶表面颜色特征的方法。该方法根据CIE色度系统三刺激值1计算式,通过光纤光谱仪分别获得茶叶和已知光谱反射率的标准白板反射光谱功率分布,计算出茶叶表面的反射率,再代入相关常量获得茶叶的三刺激值来表征茶叶表面颜色。装置采用溴钨灯作为光源,将茶叶及标准白板样品依次放入暗盒,在自编程序控制下,旋转步进电机多次采样,并利用光纤光谱仪同步接收反射光信号,对数据进行采集、储存、计算等。实验证明,该方法能快速测量出茶叶表面总体颜色,测量的重复性精度约为1%。

Surface color of tea is an important parameter to estimate the quality of tea. A method based on a fiber spectrometer to detect the surface color of tea is introduced. The reflective spectrum of tea is detected by the spectrometer and normalized by the reflective spectrum of a white standard ceramic plate. Then the CIE tristimulus values of tea are calculated according to the corresponding theoretical expressions and used to characterize the surface color of tea. A tungsten bromine light is used as light source in the experiment. The reflective spectra of tea and white ceramic standard plate are automatically and repeatedly recorded by the spectrometer. The experimental results indicate that this method is simple, rapid, and it has the reproducibility of about 1%.