Three-dimensional image creation for artificial space object by laser ranging

Abstract

Subject of Research. The paper presents a novel method for creation of an artificial space object “depth map”. The analysis of methods for creation of three-dimensional image of an artificial space object by laser locator is performed and the experimental study results are presented. The following television location methods form the basis for development. The first method of television location proposed by P. S. Vargin was developed in “Television Scientific Research Institute” (St. Petersburg, Russia). The method provides for creation of a “depth map” for remote artificial space object in a double flight time of one light pulse from the observation point to the object. The second method is used in the pulse range determination system and is based on flash-lidar performance. This system irradiates the space area of interest where the object of observation is supposed to be located; the reflected signal from the object is first recorded by a photodiode and the distance to the object is estimated. Then the object three-dimensional image is built on a certain number of points. The third method is a multi-pulse system of television laser locator based on the use of multi-pulse illumination for the study of the object under observation. Thus, it is possible to increase significantly the resolution in depth up to 10–50 mm and reduce the peak power of the laser radiation. Method. A novel method of multi-pulse illumination of an artificial space object is proposed on the basis of the considered methods in order to increase the energy of the optical signal. The method is based on the use of the charge-coupled device matrix in the mode of ultra-short accumulation time (up to 200 ns). This method enables rapid high-precision measurement of angular resolution (0.25 ang. min), range to the target (100–2000 m) and a “depth map” creation. Main Results. A laser system model was developed consisting of a television camera based on the charge-coupled device with a resolution of 752×582 pixels, a frame frequency of 50 Hz, and a laser diode with minimum pulse duration of 40 ns and a pulse repetition rate of 1 kHz. Control and synchronization of the laser is carried out by FPGA installed in the television camera ensuring the synchronization of the camera and the emitting laser. The system gives the possibility to realize interchangeable relations of distance measurement accuracy, angular and time resolution. The simulation has showed that the measurement error at small distances is less than 20 mm, and at a distance of 2000 m is less than 160 mm. Practical Relevance. The obtained results determine the characteristics of the television laser system necessary to solve the location problem for artificial space objects at a range from 100 m to 2000 m. Analysis of studies shows that modern lasers are aimed at operating in the spectral range of 1.54–1.57 μm, that reduces significantly the efficiency of the television laser system from 2 to 10 times. Therefore, it is necessary to implement laser systems with wavelengths of 0.86–1.06 microns to improve the tactical and technical properties for space inspection.