用于浮游植物探测的三维激光诱导荧光光谱系统

The Development of A 3D-LIF Spectral System for On-line Detection of Phytoplankton

本文介绍一个针对浮游植物现场探测的三维激光诱导荧光(3D-LIF)光谱系统。该系统以波长可调谐激光器为光源,使用光栅光谱仪进行光谱分光,输出光谱范围380 nm^800 nm,并选用32通道光电倍增管模组作为光电探测器。光栅光谱仪和光电倍增管模组之间的耦合选用芯径0.2 mm的光纤束,对应光谱分辨率约为3 nm,以此采集接收的31通道发射荧光光谱,其光谱范围为410 nm^710 nm,光谱带宽约10 nm。光电转换电路的模拟带宽约为20 MHz,数据采集频率50 MHz,分辨率14 bit。基于研发的光谱系统,采用光学参量放大器(OPO)以获得405 nm^615 nm可调谐激发光源,在实验室对三十余种中国海常见的浮游植物的3D-LIF光谱进行了测量。测量结果证实了系统的稳定性和用于藻种分类和识别研究的有效性。系统中的激光器和望远镜可灵活更换,接收的光谱范围和光谱分辨率等参数可便利调节,因此,该系统可望发展成为用于现场探测的3DLIF光谱系统。

In this paper,a system for measuring three dimensional laser-induced fluorescence （3D-LIF）spectra was presented.In the system a laser with multi-wavelengths output was employed as the excitation light source.A grating based spectrometer was adopted to achieve a spectral coverage from 380 nm to 800 nm.A 32 anodes photomultiplier tube from Hamamatsu was acted as the photo detector.An optical fiber-bunch,with the core size of 0.2 mm for each fiber, was used to couple the disperse signals from the spectrometer to multi-anode PMT,with a resulted spectral resolution of 3nm.The collected emission spectra have a spectral coverage from 410 nm to 710 nm with 10 nm interval.The outputs of PMT are sampled by 31 channels 50 MHz,14 bit analog-to-digital converters simultaneity.To evaluate the ability and flexibility of this system,over 30 typical red-tide species were investigated using an optical parametric oscillator （OPO） as the excitation laser source which offering a tunable wavelength range of 405 nm to 670 nm.The 3D-LIF spectra of those species had been obtained with desirable quality,showing the stability of the developed system and effective for species identification and classification.With the flexibility of optical devices and adjustable spectral parameters,such a 3D-LIF system is hoped to be developed as useful spectral system for field applications.