Research And Design Of Optical System For Water Quality Measurement Based On UV-VIS Spectroscopy

In recent years,despite the rapid economic and social development in our country,we have neglected the protection of the environment and the problem of exposed environmental pollution has become increasingly serious.In particular,the frequent occurrence of water pollution incidents has seriously affected the healthy development of people's life and social economy.Lucid waters and lush mountains are invaluable assets.Water environment protection and water quality inspection aren't been delayed.Water environmental protection and water quality detection can not be waited for.Although the traditional chemical methods has a high accuracy in measuring water quality,there are many problems,such as long detection cycle,complicated operation and Secondary pollution.UV-VIS spectroscopy water quality detection technology is becoming more and more popular as a fast and easy to operate,and no secondary pollution water quality measurement method.However,The production of optical system for spectroscopy water quality analysis instruments is mainly monopolized by foreign companies.Domestic research in related fields is in the development stage,and there are still many deficiencies in system design.For example,the coupling efficiency between the beam and the optical fiber is low,the size of the structure is large,the resolution of the photoelectric conversion system is not precise,and the interference of the stray light is too much and so on.It is too difficult to meet the demand for localization and intelligentization of the instruments proposed by the Thirteenth Five-Year Plan and the effectiveness of the River Chief System for water environment management.For these reasons above,this paper is based on the research status and development trend of UV-VIS spectroscopy water quality detection technology at home and abroad.Focusing on these problems existing in optical systems that plays a crucial role in water quality measurement,a structure scheme of water quality detection optical system integrating optical detection system and photoelectric conversion system is put forward.And the research and design of UV-VIS spectroscopy water quality detection optical system is carried out.The main research contents are as follows:(1)Studied and designed the UV-VIS spectroscopy water detection optical detection system.In view of requirements of spectroscopy water quality detection technology on theperformance of optical detection systems.In the research,the advantages and disadvantages of different light sources was compared,and the design of LED light ellipsoidal reflector and space array was completed.The research on the effects of different light intensity on the absorbance was carried out and the mechanical structure of sample pool was determined.What's more,the influence of error in fiber docking in the process of adjusting the coupling efficiency was analyzed.The ZEMAX optical design software was used to optimize the system and its performance was analyzed.The results showed that the condensing efficiency of the ellipsoidal reflector was up to 80.29%,the divergence angle of the collimated beam is less than 3.102 mrad,and the RMS radius of the entire spot after focusing is 179.626?m,which achieves highly efficient coupled transmission of beams and fibers.(2)Studied and designed the UV-VIS spectroscopy water detection photoelectric conversion system.In order to ensure the performance of water quality detection spectral analysis,the different light path structure schemes were compared and analyzed.The design of the flat field concave grating was completed,and the system structural parameters were calculated.Through the simulation,optimization and aberration analysis of ZEMAX optical design software,the results show that the designed photoelectric conversion system has better spectral resolution,which satisfies the requirements of wide spectrum and high precision measurement of water quality.(3)Studied and analyzed of the performance of the UV-VIS spectroscopy water detection optical system.The simulation and performance analysis of the whole system is carried out.The results show that the size of UV-VIS spectroscopy water detection optical system is 600mm×70mm×180mm,and the resolution of the system is less than 2nm.The entire optical system has the advantages of simple structure and small size.