Design And Implementation Of UV-Vis Absorption Spectrum Detection System

UV-Vis(Ultraviolet–visible)spectrophotometer which has the advantage of high precision,wide measurement range,high reliability,fast detection speed,convenient and quick,no secondary pollution,etc.has been widely used in biology,chemistry,pharmacy and food industry,etc.The project was based on the needs of practical application of UV-Vis absorption spectrum detection in bio-chemistry,designed and completed the construction of a new UV-Vis absorption spectrum detecter.In this paper,the absorption spectrum detection technology research development status both at home and abroad was described,the principle of the absorption spectrum detection was introduced and put forward an overall solution project,firstly.According to the overall design scheme,the system's light path was designed and fulfilled independent,the UV-Vis absorption spectrum detector were finished,the circuit and software which based on the optical cell and the PMT(Photoelectric multiplier tube)were designed.The design of test bench was also completed.Finally,debugged the system and established the test system inorder to carry on the performance and practical application test.The absorption spectrum detection principle and light path design includes analysis the requirement of system's design and performance which based on the basic principle of absorption spectrum detection technology,and determines the technical route of the system design,by comparing the light sources,the LED(Light Emitting Diode)light source was selected as the optical path of the absorption spectrum detection system.The design of system's circuit includes three aspects.1.Constant power light source design,mainly on the light source driving circuit;2.Design of absorption spectrum detector based on photodiode,including signal conditioning circuit,signal acquisition circuit,MCU circuit design and groove coupler circuit;3.Design of absorption spectrum detector based on PMT,including the signal conditioning circuit and CPLD(Complex Programmable Logic Device)pulse counting circuit.The UV-Vis absorption spectrum detection systemsoftware design carried out in three points.1.Design of the Modbus-RTU communication protocol;2.The driver software of absorption spectrum detector based on photodiode;3.Design of the driver software of CPLD pulse counting circuit and absorption spectrum detector based on PMT.The test bench was completed with four essentials.1.The power module of the main control board design;2.Design of the motor drive electric circuit;3.MCU circuit and peripheral interface circuit design;4.Design of host computer software based on Win CE.The UV-Vis absorption spectrum detection system showed human machine efficacy,stable in light resource,analysis performance well as designed and test bench function perfect after software and hardware and the whole system adjustment.The performance test and applied test results showed the absorption spectrum detection system based on the photodiode reached a span of 0-4.0 OD,0.01 OD in accuracy,R2>99.5%,RSD<0.69%;Absorption spectrum detection system based on PMT had 0-2.0 OD span,precise of 0.01 OD,R2>99.3%,RSD<0.63%,CPLD pulse counting circuit had a maximum counting rate at 1.2x108s-1,maximum count of the counting error was less than 0.2 ‰,fulfilled the demand of practical application.