Study On The Small Measurement System Of Broadband Spectrophotometry

Spectrophotometer is a kind of analytical instrument which uses spectrum to detect substances.With the continuous improvement of market demand and people’s expectation,the number of spectrophotometer demand is increasing and new requirements are put forward for its performance at the same time.In order to meet the needs of more scenes,the wide-band,miniaturized structural system has become the new development trend of spectrophotometers.This thesis focuses on the development of wide-band and miniaturized spectrophotometric systems.Aiming at the problems of complex aberrations,stray light in a wide band and the miniaturization of the system,the optimal design of the optical system is completed by establishing an optical model.Combined with the application of related theories of optics,mechanics and electronics,the construction of a wide-band miniaturized spectrophotometric measurement system was completed to meet the detection requirements of solutions with unknown concentrations.(1)Study on the correction method of the aberration of the spectrophotometer system.The system aberration is the imaging error,which is mainly caused by the optical path error.According to the design requirements,the cross type chernitna system with the highest space utilization rate is selected as the main structure of the optical system.According to the traditional optical design method,the structural design of the optical system is completed.Combined with LT software,the optical model is established,the aberration of the system is simulated and calculated,and the aberration optical model is deduced based on the idea that the optical path errors cancel each other.Through the aberration correction calculation of the optical path model,the structure optimization design of the spectrophotometer system is completed.(2)Calculation of stray light based on BSDF.In order to solve the problem of stray light in optical system,the intensity of stray light is calculated by combining BSDF scattering model and stray spectrum.According to the structure of the optical system,the spurious spectrum model is derived,and the fast calculation of the incident angle and the effective scattering angle of the spurious light is completed.The BSDF scattering characteristics of the main material black painted aluminum plate were measured by experiments.The stray light model was established based on the experimental data,and the simulated intensity of stray light was calculated.Accordingto the scattering characteristics of BSDF and stray spectrum of black painted aluminum plate,the stray light intensity is calculated theoretically.Through the comparison of theoretical calculation and simulation experiment,the feasibility and correctness of the stray light calculation method based on BSDF is verified.(3)The establishment and validation of a miniaturized wide band spectrophotometry system.According to the structure calculation of the optical system,the mechanical structure design and processing of the optical system experimental platform are completed.According to the design requirements,the selection and control of light source,motor and photoelectric detection device are completed.According to the experimental results of optical properties,it is proved that the optical system can meet the detection requirements of unknown concentration solution.In this paper,the method of combining mathematical model with LT simulation is proposed to complete the optimization design of wide band and miniaturized spectrophotometer system.The mathematical model is used to correct the aberration and stray light of the optical path.The validity of the mathematical model correction is verified by LT optical simulation.The accuracy of the optical path is improved and the design of the complicated shading parts in the optical path is avoided.It has great theoretical value and promotion significance for the Research of the wide band miniaturized spectrophotometer.