| The rapid development of microelectronics and optoelectronic equipment industry has puts higher requirements on the measurement accuracy and measurement speed of measurement systems.Dual-frequency laser interferometry has become the mainstream technical means of ultra-precision measurement technology due to its non-contact,traceable,and high-precision characteristics.As the core component of the dual-frequency laser interferometry technology,the wavelength stability,reproducibility and frequency difference of the dual-frequency laser source directly determine the highest precision and the highest measurement speed that can be achieved by the measurement.In this paper,the research status of dual-frequency laser light source is analyzed in detail,and the advantages and disadvantages of the large frequency difference dual-frequency laser source are summarized.The most cost-effective longitudinal Zeeman frequency-stabilized laser is taken as the research object.Because high-frequency stability high-frequency differential dual-frequency laser technology is blocked abroad and domestic longitudinal Zeeman lasers have low frequency difference and poor frequency reproducibility.This paper studies A high stability,large frequency difference split longitudinal Zeeman laser.Through the analysis of the relationship between the Zeeman frequency difference splitting and the magnetic field,the establishment of the magnetic field model,the design and optimization of the longitudinal Zeeman laser mechanical structure,optical path structure and control circuit,the frequency difference and frequency reproducibility of the Zeeman frequency-stabilized laser are improved.The main work of the thesis is as follows:Firstly,aiming at the problem of small double frequency difference and poor frequency stability of domestic longitudinal Zeeman laser,the relationship between Zeeman frequency difference splitting and magnetic field is analyzed,the hollow cylindrical permanent magnet structure is determined according to the uniformity of magnetic field,and the equivalent current model is used to establish the magnetic field model.Finally determined the size of the hollow cylindrical permanent magnet to ensure the strength and uniformity of the magnetic field required for Zeeman splitting,thereby improving the frequency stability of the Zeeman frequency-stabilized laser.Secondly,for the existing Zeeman frequency-stabilized laser temperature measurement module can not accurately reflect the relationship between the length of the laser tube cavity and the temperature,resulting in poor frequency reproducibility.The laser tube composite heating and temperature measurement based on the resistance thermal effect of the heating film is proposed.In the method,a heating film is attached to the wall of the laser tube as a heating element,and the true temperature of the surface of the laser tube is characterized by detecting the change of the resistance of the heating film.On the basis of this,the program of the preheating stage is redesigned to shorten the time for the longitudinal Zeeman laser to enter the frequency stabilization state and the preset temperature points are consistent at the time of frequency stabilization,thereby improving the frequency reproducibility of the longitudinal Zeeman laser.Finally,the mechanical structure,optical path structure and part of the circuit required for the longitudinal Zeeman laser are designed to integrate the large frequency difference longitudinal Zeeman laser.In order to verify the performance of the designed module and the integrated laser,a system experimental platform was built to complete the testing of the magnetic field module,the optical path module and the circuit module,and the frequency difference,frequency stability and frequency reproducibility of the system were tested.The experimental results show that the developed Zeeman frequency difference is 3.6MHz,the frequency stability is2.1×10-9 achieved within 2h,and the frequency reproducibility is 8.4×10 -9within 10 days. |
PDF Full Text Request