Powerdensity Measurement System of Laser Surgery Instrument
|School||Tianjin Medical University|
|Keywords||Laser power density Laser power Oversampling Atmega16 Range conversion|
In this thesis, the purpose of the experiment is to develop one for medical weak laser power and power density measurement of laser power / laser power density measurement system. Because the weak laser for medical and PDT treatment of the output power of the power of the laser treatment machine milliwatts magnitude to watt level, so this experiment is necessary to design a both amplifies weak DC signals but also based on the size of the change range of the laser output power, while a signal distortion lower, little interference with the amplification circuit. Because the main factors that affect medical weak laser and PDT treatment efficacy as the laser power density, the experimental average laser power density measurement methods need to be designed. In the present study, the first of the relevant information based on said inspection related method for the field of laser power and the power density measured Research and the laser power and the power of the density measurement information for the selected sensor of the thermopile sensor as a whole system. Thermopile sensor works on the basis of foreign literature to understand and determine the type of the thermopile sensor output signal for EMF signal. The analysis of the frequency domain to the frequency domain response of the the thermopile sensor output EMF signal and the noise source analysis thermopile. In this thesis, the En-In the amplifier noise models and the derivation of the corresponding formulas. Utilize the En-Iη amplifier noise model and the frequency response characteristics of the electromotive force as the basis, compared several operational amplifier chip performance, select the thermopile sensor suitable for computing amplifier chip. This thesis derived the former stage op-amp circuit system function and the preamplifier circuit frequency domain response model. This paper analyzes the preamp circuit output electromotive force signal and the doping noise frequency domain response characteristics, and designed according to the frequency domain analysis of the response characteristics of the signal processing circuit. This thesis OP07 for core range conversion circuit core to the ADS7805 high precision AD converter AD converter circuit, the Atmega16 microcontroller as the core data processing and display circuit, designed on the basis of the overall circuit. This thesis is structured design methodology designed laser power / power density measurement system software, the paper describes the overall software workflow and software subroutine works. Calibration measurement system error and the use of the mean of the sampling method approximation applied to achieve the system initial state is cleared on the main innovations of the papers in the program design. After the hardware / software FBI to obtain a laser power / power density measuring system the measured parameters such as the power value and the power density values. Through data processing and analysis can determine the present system is the laser power, real-time monitoring of the laser power density to meet design requirements, can be used for the density measurement of the average power and the average power of the continuous laser treatment system. Count as a to Gentec company SOLO PE power measurement standards, the measurement error of ± 3%, measurement accuracy of better than similar domestic products. This thesis, laser power / power density measurement system error analysis and solutions; This paper also shows a prototype made based on this study.