RESUMO
To analyze the distortion problem of two-dimensional micro-electromechanical system (MEMS) micromirror in-plane scanning, this paper makes a full theoretical analysis of the distortion causes from many aspects. Firstly, the mathematical relations among the deflection angle, laser incidence angle, and plane scanning distance of the micromirror are constructed, and the types of projection distortion of the micromirror scanning are discussed. Then the simulation results of reflection angle distribution and point cloud distribution are verified by MATLAB software under different working conditions. Finally, a two-dimensional MEMS micromirror scanning projection system is built. The predetermined waveform can be scanned and projected successfully. The distortion theory is proved to be correct by analyzing the distortion of the projection images, which lays a foundation for practical engineering application.
RESUMO
An automatic, miniature and multi-parameter on-line water quality monitoring system based on a micro-spectrometer is designed and implemented. The system is integrated with the flow-batch analysis and spectrophotometric detection method. The effectiveness of the system is tested by measuring chemical oxygen demand (COD) and ammonia-nitrogen in water. The results show that the modified system provides a cost-effective, sensitive, reproducible and reliable way to measure COD and ammonia-nitrogen in water samples with automatic operation and low toxic chemical consumption. In addition, the experiment results show that the relative error of the system is less than 10%, the limit of detection is 2 mg/L COD and 0.032 mg/L ammonia-nitrogen, respectively, and the relative standard deviation was 6.6% at 15.0 mg/L COD (n = 7) and 5.0% at 0.300 mg/L ammonia-nitrogen (n = 7). Results from the newly designed system are consistent with the data collected through the Chinese national standard analysis methods.
