冠层反射光谱测量中主动光源光谱稳定性控制  

Control Stability of Active Light Source Spectra during Measuring Reflectance of Canopy

作　　者：丁永前[1] 李杨[2] 谭星祥 曹卫星[1] 朱艳[1] 

机构地区：[1]南京农业大学国家信息农业工程技术中心,南京210095 [2]南京农业大学江苏省现代设施农业技术与装备工程实验室,南京210031

出　　处：《农业机械学报》2014年第6期284-290,共7页Transactions of the Chinese Society for Agricultural Machinery

基　　金：'十二五'国家科技支撑计划资助项目(2013BAD08B04);中央高校基本科研业务费资助项目(KYZ201127);江苏高校优势学科建设工程资助项目

摘　　要：结合自主研发的冠层反射光谱测量装置,对装置主动光源采用的波长730 nm和810 nm两种窄带LED的光谱稳定性进行了研究。实验结果表明:两种LED在未加特殊控制、按照测量要求高频脉动点亮时,结温均显著升高,造成光源光谱峰值波长的线性红移和发光强度的线性降低,严重影响测量装置测量结果的稳定性和可靠性。提出了一种间歇式脉动驱动LED的方法,该驱动方法使LED工作时结温的升高幅度保持在2℃以内,峰值波长的波动小于1 nm。最后该驱动方法被嵌入到反射光谱测量装置中,进行了室内及田间稳定性测试实验,反射光谱响应值最大相对波动率小于5%。With the self-developed measurement equipment of canopy reflection spectrum, the spectral stability of two kinds of narrowband-LEDs, which were used as active light sources and had peak wavelengths of 730nm and 810nm respectively, were studied. The experimental results showed that the junction temperature of the LEDs was significantly increased when the LEDs were pulse-lighted in high frequency based on the request of the measurement. The increased junction temperature resulted in linear red-shift of the light source spectra and linear decrease of luminous intensity of the light source, which seriously affected the stability and reliability of the measuring results. A new method of driving LEDs, named intermittent pulse-driving LED, was proposed. When LEDs were driven in this method, the rise of the junction temperature could be effectively controlled below 2℃ , and the red-shift of peak wavelength of light source spectra was less than 1 nm. Finally using the self-developed measurement equipment of canopy reflection spectrum, in which this method was embedded, the experiments were implemented both in laboratory and wheat field to measure the reflectance response of the crop canopy. The fluctuation ratio of measured results was less than 5%. The LED-driving method proposed could be applied in developing measuring equipments for detecting reflection spectrum of crop canopy.

关 键 词：作物冠层 反射光谱 主动光源 光谱稳定性 

分 类 号：S123[农业科学—农业基础科学] TP702[自动化与计算机技术—检测技术与自动化装置]