Research on calculation method of vertical axis error for photoelectric theodolite

The vertical axis is the reference axis of the photoelectric theodolite, and it is an important part that affects the measurement accuracy of the photoelectric theodolite. Therefore, it is necessary to measure, calculate and correct the vertical axis error of the photoelectric theodolite during the execution of the test task to ensure the accuracy and validity of the test data. The harmonic method to measure and calculate the vertical axis error of the photoelectric theodolite has a cumbersome process and complicated calculation. Aiming at the shortcomings of the harmonic method ,this paper establishes a new mathematical model for measuring the vertical axis error with a spirit level, and deduces the calculation methods in two cases. The comparison of the actual data calculation results shows that the calculation results of the method in this paper are consistent with the calculation results of the harmonic method and meet the test requirements. In addition, the method in this paper needs less measurement data and the process is simple, which is suitable for shooting range applications, which is more conducive to improving the testing ability of photoelectric theodolites, and also provides a reference for the accuracy analysis and error correction of photoelectric theodolites.