The Reaserch On The Online System To Measure Algae Consisitence By Fluorescence

Algae is the major component of marine ecosystem, while chlorophyll-a is the mahor pigments in algae. Thereby, chlorophyll-a is an improtant characteristic of marine ecosystem, it's of great importance to the observe and research sea water, and it's a necessary factor to detect sea water and change trend. Now, one important topic of the marine measurement technology is the real online detection for algae, and people all over the world pay more and more attention to design and manufacture kinds of sensors, in which LED is uesd as light source. This system achieves detection on-line by using LED resources, fluorescence technique and MCU technique, based on the unit concentration available. The main contents of study is as follows:Firstly, the basic theory and characteristic of fluorescence technique is introduced,and the fluorescence characteristic of chlorophyll-a is analysed, providing fundamental basis for finding reasonable excitation light source, filter, optical path and sensors.And the general concept for fluorometric method is designed, and a mathematical model for fluorometric method is constructed according to the structure of sensors, providing fundamental basis for the measurement in system.Secondly, the emitting, collection, processing and transmittion of weak fluorescence signal is achieved by choosing narrow bandwidth LED as light source, choosing photodiode which is able to catch scintillation as the detector, and using the MCU to collect and process data.The high quality blocking factor filters is adopted to eliminate the influence of excitation light source. Meanwhile carrier wave is added to fluorescence signal to eliminate the noise outside.Finally, the diffiency of measurement is concluded and data-compensation program is drawn up, comparing with the known algae consistency. In the end, the feasibility to detect algae online is proved by classfication.