Device and method for detecting concentration of algae in water body through chlorophyll fluorescence induced by near ultraviolet laser

Abstract

The invention discloses a device and a method for detecting the concentration of algae in a water body through near ultraviolet laser induced chlorophyll fluorescence, and belongs to the field of photoelectric detection. According to the method, a near ultraviolet semiconductor laser with the wavelength being 405 nm and the power being 100 mw is adopted as an excitation light source, emitted laser beams are subjected to two-dimensional beam expansion through a quartz cylindrical lens to form fan-shaped light, the fan-shaped light is vertically irradiated to a water body sample containing algae, after chlorophyll a contained in the algae in the water body sample is excited, fluorescence with the wavelength being 685 nm is emitted, the silicon photocell receives and generates an electric signal, and the concentration value of algae in the algae-containing water body is determined by measuring the voltage value corresponding to the fluorescence intensity. The device is simple in structure, good in stability, low in cost and high in precision, chlorophyll fluorescence signals can be detected even under the condition that the concentration of algae in the water body is very low, and on-site real-time multi-point detection of the concentration of the algae in the water body can be achieved.

Description

technical field [0001] The invention relates to a near-ultraviolet laser-induced chlorophyll fluorescence detection device and method for algae concentration in water, belonging to the field of photoelectric detection. Background technique [0002] Chlorophyll widely exists in algae and other phytoplankton in water, and the content of chlorophyll a is the highest, which is the main indicator to measure the biomass of algae in water body. Therefore, the determination of the concentration of algae in water can be achieved by measuring the concentration of chlorophyll. At present, the main methods for determining the concentration of chlorophyll are spectrophotometry, high performance liquid chromatography, remote sensing, fluorescence and so on. Among them, spectrophotometry and high-performance liquid chromatography belong to laboratory analysis methods, which are highly specialized, low in efficiency, long in the analysis cycle and unable to carry out real-time monitoring. ...

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Problems solved by technology

[0003] The shortcomings of the existing fluorescence method are as follows: firstly, the excitation light source commonly used in the fluorescence method is: LED excitation light source, because the light power density of the LED light source is relatively small, the fluorescence signal excited will be relatively weak, and the directionality is poor; secondly, the fluorescence A photoelectric sensor with a small photosensitive area is commonly used in the method. The smaller the photosensitive area of ​​the photoelectric sensor, the smaller the received fluorescent light flux. It may be lost in the noise, and the concentration of algae in the water body cannot be measured; finally, in the fluorescence method, the traditional spherical mirror is often used to converge the beam, but the beam passing through the condenser still diverges to form a light cone in the three-dimensional space, and the luminous flux entering the cuvette will be very large. Small, the chlorophyll fluorescence generated by excitation is weak

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