Study On Alignment Technology Of A Scanning Infrared Thermal Imager

According to the performance index of infrared thermograph MRTD(minimum distinguishable temperature difference),the assembly and debugging process of the infrared thermal imager are analyzed.The necessary analysis,test and verification are taken from the adjusting technology and testing methods,the research on key technology of installation and adjustment is carried out,the adjustment process is improved and the test worker is improved.The art scheme solves the serious cold reflection phenomenon of the infrared thermal imager.The thesis is mainly analyzed from the following three aspects:1)the measurement of the performance MRTD of the traditional infrared thermograph,the measurement error is large,the repetition rate is low,and it is influenced greatly by the subjective factors of the tester and the fitting result of the measurement of the hot target curve,which seriously affects the performance of the infrared thermograph performance MRTD measurement.According to the traditional infrared thermal imager performance MRTD measurement method,according to the principle of infrared technology and imaging system and the principle of using the finite distance imaging test to solve the problem that the test target is not necessary for the curve fitting calculation result,a improved MRTD measurement method adapted to the current product performance is proposed to make the performance of the infrared thermograph.The test error of MRTD is reduced and the repetition precision is improved.2)the large object lens of the telescopic system is the maximum weight and volume of the optical system of the entire infrared imager(6kg).It is located at the outside of the optical system and is directly exposed to the air to resist the temperature change,the air corrosion and the vibration shock,and also to receive the infrared radiation information of the object.Therefore,a higher requirement for the assembly quality of the large object lens in the telescopic system is put forward.The assembly process of the existing large objective lens is improved from the bonding process of the object mirror and the mirror tube and the measurement method of the objective of the objective lens.A bonding method is combined with the method of pressing ring,and an elastic diaphragm is added between the pressure ring and the mirror.Way.When the telescopic system is subjected to vibration and shock,the lens and the lens tube are separated by the rubber layer and the elastic diaphragm,and the hard contact is changed into elastic contact,and the assembly stress is reduced to ensure the imaging quality of the telescope.At the same time,the end face of the lens surface which is contact with the lens surface is curved in accordance with the curvature of the lens surface to increase the contact area of the end of the boundary frame and the surface of the lens.The assembly stress is reduced in the near step to meet the requirement of the performance of the infrared thermal imager MRTD.3)the optical interval between the lens,the mirror group and the scanner in the optical system of the infrared thermography must be accurate,the greater the error of the optical spacer,the more blurred the image of the infrared thermograph.Therefore,the advanced optical interval measurement technology is studied,and the method of ensuring effective and reliable optical interval is also discussed.Through the discussion of this paper,the assembly and debugging methods of the lens and lens assembly of the infrared thermal imager and the MRTD measurement method of the performance of the infrared thermal imager are improved.After that,the actual use of a certain type of thermal imager is verified.When the space frequency is 6.172 cyc/mrad,the average value of the MRTD index for measuring the performance of a certain infrared thermograph is 0.685K after using the measurement method of the performance MRTD of the improved infrared thermal imager,which is far less than the requirement of 1.2K,and there is no serious cold reflection phenomenon in the picture.To meet the requirements of use.At the same time,by adopting the improved MRTD measurement scheme,the repeatability error of the measurement is controlled to less than 23%,and the MRTD data measurement results are closer to the real situation.It is proved that the improvement scheme is feasible...