| High precision displacement sensor is an important symbol of the development level of a country's manufacturing industry.Optical displacement sensor is the main high precision displacement sensor,and the most widely used are the laser interferometer and the grating.The former light path is directly exposed to the working environment,which has the shortcomings of poor anti-interference,high requirements on the working environment and high manufacturing cost;The latter measurement precision depends on the manufacturing precision of the grid spacing and spatial subdivision,so there are some constraints such as difficult manufacturing technology and extremely expensive grating ruler manufacturing equipment.Therefore,the research group of the author carried out the study on the high-precision light field time-grating sensor which can reduce the manufacturing difficulty.Based on the verification of measuring principle of the single light field time-grating sensor,the light field distribution characteristics are deeply analyzed,and the analysis and optimization of light field distribution error are studied in this paper.The main research work is as follows:(1)The distribution characteristics of collimating light source are deeply studied.The secondary distribution design of light intensity uniformity and collimation is studied,and the simulation model of light source with light intensity uniformity and the simulation model of light source with light intensity uniformity and collimation are established.Comparing with the light intensity distribution curve of the actual LED,the analyzing method of the light field distribution characteristics using the light source simulation model is further optimized.At the same time,in order to analyze the light field distribution error in detail,the above simulation model of light source is introduced into the sensor model to study the light field distribution error.(2)The optimized method to compensate the light field distribution error is studied.According to the distribution characteristics of light source,the error theoretical model of uniformity of light intensity and the error theoretical model of scattering angle are established respectively,and the light field distribution errors are analyzed by theoretical models.At the same time,the light transmission surfaces and the arrangement structure of light transmission surfaces are analyzed by theory and simulation,and an optimization method of the continuous cosine light transmission surfaces with the central symmetric distribution is proposed.(3)A time-grating sensor prototype of single light field was developed,and contrast experiments are carried out with a variety of structures of light transmission surfaces.The experiment verifies the correctness of the analysis of the light field distribution characteristics,and the experiment result showed that according to the prototype sensor by the light field distribution errors are optimized,the error is reduced from 0.79 ?m to 0.4 ?m in the period,The deviation between the measurement values and the reference values is within ±2.7 ?m with grid spacing of 0.6 mm in the measuring range of 500 mm.In summary,this paper makes an in-depth study on the light field distribution characteristics of light source from simple to complex,the light field distribution characteristics of lambertian-type LED,and the light intensity uniformity and scattering characteristics after collimation are analyzed.At the same time,the light field distribution errors are analyzed in detail,the corresponding optimization method is put forward,and the miniaturization time-grating sensor prototype is developed.The above research establishes a theoretical and practical foundation for the realization of high precision measurement and later marketization of light field time-grating sensor. |
PDF Full Text Request