Research On The Primary Mirror And Supporting Structure Of Photoelectric Theodolite With 1m Aperture

The flight status of the experimental object can be detected in real time and real-time images can be output while the motion parameters and flight attitude can be record by the photoelectric theodolite.The measurement results are accurate and not easy to be interfered.One of the most important part of the optical system of the photoelectric theodolite is the primary mirror in that the imaging quality of the photoelectric theodolite determined by the surface figure precision of the primary mirror.The most important factor influencing the surface figure precision of the primary mirror is the supporting structure of the primary mirror.Therefore,in order to ensure the accuracy and system stability of the photoelectric theodolite during operation,the design of the primary mirror and its supporting structure of the theodolite meets the engineering requirements are necessary.In this paper,the 1m diameter primary mirror and supporting structure are taken as the research object.The primary mirror and supporting structure is completed by using empirical formulas and finite element analysis.Then the structure of the primary mirror is optimized.First,the evaluation principle and analysis theory of the surface figure precision of the primary mirror are explained.After comparing and analyzing the characteristics of various support methods,it is determined that the axial support form of the primary mirror is 18-point mechanical whiffletree support,the radial support form is vertical push-pull support,and the mandrel is designed to locate the primary mirror.The finite element analysis is used to optimize the distribution radius of the supporting points to reduce the surface error of the primary mirror under the action of the supporting structure.Secondly,in order to keep up with the development trend of photoelectric theodolites,the lightweight design of the primary mirror is carried out.Then the lightweight primary mirror is optimized,including the optimization of the parameters of the primary mirror and the structural optimization of the primary mirror with the use of stiffeners.Then,the static and dynamic analysis of the primary mirror under the combined action of gravity and the supporting structure is carried out.Trend of the primary mirror’s surface figure precision under different pitch angles is discussed,and the natural frequency and vibration mode of the primary mirror with different structures are compared and analyzed.Finally,the thermal analysis of the primary mirrors with different structures is accomplished.The variation trends of the surface figure precision of the primary mirrors under different temperature fields is discussed.In a steady-state temperature field,trends of primary mirrors which has same material and different structure is basically the same.Under the temperature gradient field,trends of the surface figure precision of the primary mirror with different structures is the same,but the amplitude is different.Compared with the axial temperature gradient field,the radial temperature gradient field has a smaller effect on the primary mirror.