Research On High Stability Of Spaceborne UV-LED Calibration Circuit And Control Technology

At present, the international mainstream on-board calibration is sun calibration、blackbody calibration and lamp calibration. As an important technical means, the lamp calibration has played a very important role for the space remote sensor calibration. Lamp calibration refers to using the lamp as the standard source to recalibration the responsivity and the spectrum of the space remote sensor. The calibration cycle and the scan cycle should be consistent. It needs to reduce the stable time and improve the stability of the light intensity to meet the requirement of the instrument spectral region and radiation sensitivity. UV LED(Ultraviolet Light Emitting Diode) has good stability、long life-time、small volume、high luminous efficiency、low power consumption、strong resistance to vibration and many other advantages, make it very suitable for use in harsh environment of space. In recent years, the domestic in the use of the UV LED as the calibration source is still in its infancy. It is of great significance to the development of domestic related fields to carry out the UV LED calibration technology research actively.For the problems of general LED drive circuit, such as long stable time、low stability and uncontrollability current. On the premise of full investigation of the UV LED’ performance and drive circuit, a digital control circuit based on FPGA is designed to drive the UV LED and incremental PID closed-loop control method is used. Under different environment such as normal pressure and temperature、various temperatures and vacuum, we have performed many experiments and obtained the relationship between the current change over time, and the corresponding relationship between the current and the illumination intensity.The highlight of this dissertation is summarized as follows:1 For the requirements of space remote on-board calibration, explored the feasibility of using UV LED as the calibration source, analysed the method of UV LED on-board calibration, ensured that the UV LED light intensity stability as the core, compared and researched the high stability of UV LED drive scheme.2 A digital control circuit based on FPGA is designed to drive the UV LED and incremental PID closed-loop control method is used. Compared with the traditional LED drive circuit, this system can have big current range, strong adjustability and high degree of stability. With the good cooling condition in vacuum, this system can make the UV LED at the typical current 200 mA achieve a sense of stability in ten seconds, and the unstability of the current is not greater than 1‰ in thirty minutes, meet the requirement of the on-board calibration.