| Solar simulator is an important equipment for space environment simulation,which is used to provide a controllable radiation source, and which radiation features such as the spectral distribution, uniform and stable are similar to the sun, for the thermal test requirement of the spacecraft, the calibration test of satellite attitude parts,environmental adaptability test of optical remote sensor, power generation of solar photovoltaic, material properties test and so on. Most of solar simulators mainly consist of the source system, the homogenies system and the imaging system, and the structure of the optical system directly determines the irradiance, uniformity, stability , spectral distribution and other physical characteristics of the irradiated surface, and the size of the irradiated surface ,the quasi-right angle and other geometric features. So, the study of solar simulator is one of most critical issues of the system to improve energy efficiency and uniformity of lighting, which has been the focus of solar simulation technology research.In this paper, the design theory and research methods of the solar simulator are discussed in depth. According to the development course of the solar simulator, the optical design principle and the optical structure of the solar simulator are analyzed and summarized. In the optical design of the solar simulator, it is need to consider the factors such as the utilization of light energy, the uniformity of illumination and the quality of the imaging beam. It must be combined with the optical theory of imaging optics and non-imaging optics to improve the optical performance of the traditional solar simulators.At first, the basic concepts of non-imaging optics theory are introduced in this paper,and the optical expansion (etendue) is used to analysis the energy process of the solar simulation system. The optical expansion of the source arc, the ellipsoid condenser and the optical element is analyzed in detail. The relationship between the amount of expansion and the energy utilization efficiency of the system is dicussed, which providing a basic theory and optimization method for the calculation of the energy efficiency of the solar simulator.Illumination uniformity of solar simulator is also analyzed in this paper. Based on the basic principle of illuination, the model of uniform illumination of solar simulator is established by multi-channel Kohler illumination method, and the main factors of influence illumination uniformity is analyzed in detail. It has been pointed out that increasing the number of lenses, reducing the diffraction effect and controlling the aberration of the condenser will improve the uniformity of the irradiation surface. It is provided that a useful reference for the optical design of solar simulators in this paper.Finally, based on the theoretical research, a collimated solar simulator and a projection solar simulator are designed, and the process of optical system design and the test result of the solar simulator are introduced. A rod optical integrator is designed to improve the uniformity of illumination. A new collimated optical system and an object telocentric projection optical system are designed to improve the optical performance of the traditional coaxial solar simulator. The result of the system simulation analysis and the actual test prove that the optical system design is reasonable.The future development trend of the solar simulator is also analyzed. It is provided in this paper that a reference for the future solar simulators which have the miniature size,high efficiency and good performance. The study of solar simulators promotes the development of the space environment simulation technology, and has a very important practical significance. |
