With the development of high-resolution imaging infrared remote satellites, high resolution imaging and wide swath width are required. Now one effective way to get a wide imaging swath is to increase the length of infrared chip linear array. Restricted by the number of sensor elements on each chip, field butting of the multiple chips is often adopted to obtain a wide of the field of view (FOV). However, since each infrared chip is actually an array in physical structure, and there is also an outer cover for each chip, it is really impossible to place the multiple infrared chips directly as a straight line on the focal plane, and three non-collinear arranging style is adopted instead. Due to the control stability of the drift angle, a non-collinear arrangement of the three chips on the focal plane, the undulation of the ground elevation and so on, the sub-image separately captured by each infrared chip cannot directly from as an integrated image scene. In this paper, the image mode of the three non-collinear Infrared chips is proposed. What is more, some key factors that affect the imaging quality of the three non-collinear infrared chips are discussed in detail, including the control of the drift angle, the placement of the three infrared chips on the focal plane, the terrain undulation and so on. The scales of the effect caused by those factors are calculated in the paper. In order to test and verify the methods given in the paper, flight mission of sun synchronism circle orbit is taken as an example for simulation. Some practical conclusions are arrived at. When the drift angle is out of control, it can bring the effect of the drift angle on the overlapping degree about pixel number, and relative distortion variation tendency was given based on altitude difference.
Thermal radiation is an inherent property of all objects. Generally, it is believed that the body, which temperature is above absolute zero, can keep generating infrared radiation. Infrared remote sensing, using of satellite-borne or airborne sensors, collects infrared information to identify the surface feature and inversion of surface parameters, temperature, etc. In order to get more accurately feature information, quantitative measurement is required. Infrared radiometric calibration is one of the key technologies of quantitative infrared remote sensing.
Most high-resolution thermal imaging systems are cooling. For the infrared optical system which is having a cooled detector, there are some special phenomenons. Since the temperature of the detector’s photosensitive surface is generally low, which is very different from system temperature, it is a very strong cold radiation source. Narcissus refers to the case that the cooled detector can “see” its own reflecting image, which may affect the image quality of infrared system seriously. But for radiometric calibration of satellite-borne infrared camera, it can sometimes take advantage of the narcissus instead of cold cryogenic radiometric calibration. In this paper, the use of narcissus to carry out radiometric calibration is summarized, and simulation results show the feasibility.
Infrared camera, which works on cryogenic or normal temperature, has thermal radiation inside. It is called interior radiation. In the space optical remote sensor, interior radiation will produce a lot of bad effects. Firstly, it can depress image contrast. What is more, dynamic range and integral time will be decreased. Lastly, interior radiation is one of the main factors that affect the measurement accuracy. So, restraining interior radiation is one of the key technologies to enhance the quality of infrared thermal imaging technology. In this paper, the typical technology of restraining interior radiation is summarized. At the end of the paper, blue prints for restraining interior radiation are proposed.