Development of the high-resolution,high-sensitivity,large-width thermal infrared camera for 5 m Optical 02 Satellite
Thermal infrared images are widely used in the field of land resource management,fire detection,and missile warning and surveillance.To improve China's ecological management and strengthen the supervision of high-energy-consuming enterprises(e.g.,steel plant),the requirements for the development of a high-resolution,high-sensitivity,and large-width space thermal infrared camera are proposed.On this basis,the thermal infrared camera installed on the 5 m Optical 02 Satellite was designed and developed.The thermal infrared camera was successfully launched at the Taiyuan Satellite Launch Center on December 26,2021.The thermal infrared camera adopts an advanced push-broom imaging system and uses an 8192 pixel long-line array long-wave infrared detector to obtain thermal infrared images in the 7.7-10.5 μm spectrum.It chooses an off-axial three-mirror main optical system and a transmission system with free-form surfaces to achieve an 8.6°× 1.1° field of view.The absolute distortion of the optical system is less than 1 μm,the average MTF is better than 0.32,and the uniformity of the focal plane illumination is better than 0.98.The focal plane of the thermal infrared camera is composed of eight CCDs.The number of pixels of each CCD is 1024×6×2.Time delay and integration technology is used to improve the SNR ratio.The material deformation matching method is used to ensure the thermal stress and displacement meet the requirement at a low temperature of 80K.The thermal infrared camera also uses cryogenic optical technology to reduce the system background noise and improve the dynamic range of the camera.Three lens close to the focal plane work at 200 K.The cryogenic lens is cooled by a pulse tube cryocooler.At the same time,a calibration mechanism and focusing mechanism are installed inside the thermal infrared camera,which can realize on-orbit radiation calibration and focal plane adjustment.These designs improve the radiometric accuracy and reliability of the camera.After completion of the detailed design,the thermal infrared camera has a ground sampling distance of 15 m and a coverage width of 120 km.The NETD of the thermal infrared camera is better than 0.1 K@300 K.The thermal infrared camera achieves high-resolution,high-sensitivity,and large-width observation simultaneously.After the alignment and ground test of the thermal infrared camera,the average MTF of the entire field of view reaches 0.151,NETD reaches 0.06 K@300 K,dynamic range exceeds 240-340 K,and linearity of the radiometric calibration curve is better than 0.99.After the 5 m Optical 02 Satellite was launched,the on-orbit test was completed.The image geometric performance and radiation performance on-orbit are excellent,and the resolution and width meet the requirements.An analysis of the image data of high-temperature and low-temperature ground objects near 300K indicates that the on-orbit NETD is close to 0.08K,and the absolute radiation calibration accuracy on-orbit is better than 1 K.Compared with the GF-5 02 VIMS launched in China in 2021 and the Landsat 9 TIRS-2 launched in the United States in 2021,the thermal infrared camera onboard the 5 m Optical 02 satellite has greatly improved the resolution and maintained a large width.At the same time,the NETD is close to the best in the world.The thermal infrared camera can well support businesses related to land resources.
remote sensingthermal infrared camerapush-broom imaginginfrared detector5 m Optical 02 Satellite
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