Research On High Temperature Field Measurement Method Based On CCD

In modern metal heat treatment technology,temperature and its distribution as an important factor in the production process affect the performance of the product,so how to measure the high temperature field becomes particularly important.At present,the traditional contact high temperature measurement method has problems such as low temperature measurement efficiency,and difficulty in measuring the temperature field distribution.Although infrared thermal imaging equipment can obtain a wide temperature field distribution,it is not suitable for high temperature measurement,and has a complicated structure and expensive price.The near-infrared CCD-based high temperature field measurement method is a non-contact temperature measurement method that combines modern digital image processing technology based on traditional radiation temperature measurement technology.It has the characteristics of simple structure,high accuracy,and low cost,And can accurately measure the temperature field of high temperature targets.According to the actual specific requirements of the rapid temperature change and wide temperature range of the laser heat treatment temperature field,the design of the high temperature field measurement system based on the near-infrared CCD is designed to calibrate the mapping relationship between the radiation temperature and the gray scale of the image.First of all,in view of the characteristics of rapid temperature change,an adaptive exposure control algorithm for a rapidly changing temperature field is proposed.By quickly adjusting the exposure time to switch to a suitable temperature measurement segment,the measurement of a fast changing temperature field is achieved.Aiming at the characteristics of a wide temperature range,a segmented measurement method of a wide temperature field is proposed.The adaptive exposure control algorithm with a fast changing temperature field is used to obtain the minimum exposure time.The narrow temperature fields under multiple exposure times are synthesized from wide to small in order.Temperature Field.Secondly,an error analysis is performed on the calibration process and measurement process of the mapping relationship between radiation temperature and image gray scale,and a correction method is proposed.In particular,in order to improve the temperature measurement accuracy,a CCD pixel non-uniformity correction model,a distance error gray correction model,and a fast bilateral filtering denoising method were improved.Finally,the software design of the temperature measurement system was completed,and infrared image processing and pseudo color and three-dimensional image display were realized.The feasibility of the system was verified by measuring and testing the temperature field of laser heat treatment on T10 steel surface.The inversion of the calibration results yielded good results with a temperature range of 800-1480 ° C(spectral emissivity of 1)and absolute temperature error of less than 0.66%.It shows that this method is a low cost,high stability,high precision,simple and effective temperature measurement method,and can provide a practical solution for high temperature measurement in industrial production.