Establishment and Error Analysis of Model of Interference Fringe Contrast for Laser Tracing Measurement Optical System

A method was proposed to analyze the influences of the non-ideal spectroscopic performance of optical components and orientation errors of a laser tracing measurement optical system on the tracing measurement performance.A comprehensive model of the interference fringe contrast based on the laser tracing system s measurement principle was established in this study.Simulation results based on ZEMAX verified the model.According to the simulation results,the placement angle of the analyzer had a direct influence on the interference fringe contrast.When the angle of the polarized light to the analyzer’s transmission axis increased from 65°to 85°,each contrast of the four-way interference fringes decreased from 0.9996 to 0.3528,the interference fringe contrast is decreased by 65%.Under the split ratio of beam splitters in the interference part(BS 1)of 5∶5,when the splitting ratio of BS 2 changed from 2∶8 to 8∶2,the fringe contrast of the interference signals received by the photodetectors increased,but the injection light intensity onto the PSD reflected by BS 2 decreased.The significant influence of the tracing performance was verified by the experiments.When splitting ratio of BS 2 increased,the contrast of the interference fringes increased.Due to the weakening of the incident light intensity of the PSD caused by the change of BS 2 splitting ratio,the response time of the tracing system is increased by 23.7 ms.As a result,the tracing performance of the laser tracing measurement optical system was degraded.An important theoretical basis was provided to evaluate and improve the accuracy and reliability of laser tracing measurement systems.

A scientometric review of biochar preparation research from 2006 to 2019

Biochar is the carbon-rich product obtained from the thermochemical conversion of biomass under oxygen-limited condi-tions.Preparation methods contribute to biochar properties,which are widely concerned in the agronomic and environmental benefits of agro-ecosystems.This research aims to use bibliometrics methods to comprehensively and objectively analyze the research trends in the global biochar production field from 2006 to 2019 based on the Web of Science Core Collection database.The results showed that 1434 papers related to biochar preparation were published,which gradually increased each year.The research topics were diversified,which were mainly divided into“Environmental Sciences and Ecology,”“Engineering”and“Agriculture”.Moreover,Bioresource Technology was the most published journal contained biochar preparation.Authors from China had the most publications,followed by the US,Australia and the UK.Meanwhile,Yong Sik Ok from Korea University contributed most of the publications and had the highest H-index.Keywords analysis indicated that biochar preparation by pyrolysis was a current hotspot,of which microwave and hydrothermal were a future research trend.Besides,gasification would be used to develop new biomass energy.Biochar has the characteristics of high pH,high specific surface area,high carbon content,and rich functional groups.It is mainly used in soil improvement,water pollutant adsorption,carbon sequestration and emission reduction,and energy storage materials,etc.Furthermore,raw materials,pyrolysis temperature and pyrolysis time will also affect its characteristics and applications.It is expected that this study may provide insight into the future research interests regarding biochar preparation.