Multichannel optical dissolved oxygen measurement device and measurement method

Abstract

The invention discloses a multichannel optical dissolved oxygen measurement device and a measurement method. The device comprises a sealed housing, an excitation light source module, a fluorescent light generation module, a multichannel fluorescent light receiving module, a signal processing unit, a data acquisition and control unit and a computer processing unit, wherein the excitation light source module, the fluorescent light generation module, the multichannel fluorescent light receiving module, the signal processing unit and the data acquisition and control unit are arranged in the sealed housing; the computer processing unit is arranged outside the sealed housing; the multichannel fluorescent light receiving module comprises three identical fluorescent light receiving channels; fluorescent light receiving angles are 45 degrees, 60 degrees and 90 degrees from a plane where the fluorescent light generation module is located; and the three fluorescent light receiving channels are located in the same plane and isolated from one another. The fluorescent light receiving channels are employed to improve fluorescent light receiving efficiency; in addition, a fluorescence intensity ratio of every two channels is used to achieve correspondence between the ratio and oxygen concentration; the disadvantage of a measurement error caused by susceptibility of the existing fluorescence intensity-based detection method to instability of light source is overcome; and a measurement result of dissolved oxygen is more accurate.

Description

technical field [0001] The invention relates to a multi-channel optical dissolved oxygen measuring device and a measuring method, belonging to the technical field of dissolved oxygen measurement. Background technique [0002] With the development of optical sensors, fluorescence analysis and measurement technology has been widely used in the detection of dissolved oxygen concentration in water. The optical dissolved oxygen measurement method based on the fluorescence quenching mechanism has gradually replaced the traditional iodometric method and oxygen electrode method. The detection of dissolved oxygen concentration is of great significance in the fields of industry, agriculture, medicine and environmental monitoring. [0003] However, in many existing technologies, such as an invention in China (publication number: CN 1731154A) and a utility model (publication number: CN 2014788947 U), both of them use a measurement method based on fluorescence intensity to determine The...

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Problems solved by technology

[0003] However, in many existing technologies, such as an invention in China (publication number: CN 1731154A) and a utility model (publication number: CN 2014788947 U), both of them use a measurement method based on fluorescence intensity to determine Dissolved oxygen concentration in water, which will bring errors due to light source fluctuations and other factors, reducing the sensitivity of the system and the accuracy of measurement results

Although the measurement method based on the fluorescence lifetime has improved the measurement accuracy, the measurement process is relatively complicated and the measurement time is relatively long.

[0004] In addition, most of the measurement methods based on fluorescence intensity use a single-channel optical receiving structure, which directly realizes the measurement of dissolved oxygen through the corresponding linear relationship between the generated fluorescence intensity and the dissolved oxygen concentration. Due to the change of light source intensity, it will undoubtedly increase. Measurement error, resulting in low measurement accuracy of the system

Moreover, the fluorescence generated by excitation is a kind of scattered light, and the single-channel optical receiving structure itself will also reduce the receiving efficiency of fluorescence, which will bring the disadvantage of a small measurement range of dissolved oxygen concentration, which is also not conducive to the practical application of dissolved oxygen measurement system develop

[0005] Further, for the measurement of dissolved oxygen, optical fiber is also used to realize the transmission of excitation light and the reception of fluorescence. If laser is used as excitation light, due to the high energy, this will greatly shorten the life of the fluorescence sensitive film, while using light emitting diode (LED), It is necessary to consider how to efficiently couple the excitation light source and fluorescence into the optical fiber. Even if the LED light source with pigtail output is used, it will undoubtedly increase the cost

At the same time, most of the fiber-optic dissolved oxygen measurement devices are a discrete detection structure, resulting in low integration of the entire measurement system

[0006] Finally, in many existing technologies, when the method based on fluorescence intensity is used to measure dissolved oxygen, the accuracy of the method used is not very high in the process of collecting fluorescence signals to data analysis, processing and linear fitting, such as the least square method, The detection of dissolved oxygen concentration not only requires high-precision data processing circuits, but also requires good data processing and linear fitting methods

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