| With the continuous development of laser technology,the application requirements of high power and multi-wavelength lasers in various fields such as laser active interference and industrial processing are increasing.However,due to the influence of thermal damage,nonlinear effects and other factors,the output power of a single laser is limited,and it is difficult to obtain multi-wavelength laser coaxial output.Laser beam combining is still an effective method to obtain high power and multiwavelength laser coaxial output at this stage.The visible light band multi-channel laser wavelength combining system designed in this research is the input end of the laser active jamming system and the core component of the laser active jamming system.According to the function and requirements of the laser beam combining system,this paper uses wavelength beam combining to combine multiple lasers with different wavelengths.A variety of laser beam monitoring technology and laser beam control technology are compared and analyzed,and the beam combining scheme of the designed laser beam combining system is finally determined.Firstly,the pointing deviation and position deviation of each unit beam are obtained by the laser beam pointing monitoring device and the beam position monitoring device respectively.Then,the movement of the beam adjustment device is controlled by the servo control system,including the rotation of the two-dimensional steering mirror,the translation of the high and low position adjustment device and the left and right position adjustment device,and the correction of each laser is completed one by one.Finally,the precise beam combination of multiple lasers is realized.Through the control strategy of single laser pointing and position alternating correction and multi-laser sequential cycle correction,the closed-loop control of multi-laser is realized periodically,and the beam combining accuracy and stability of the beam combining system working for a long time are ensured.After completing the processing and adjustment of each device of the beam combining system,a laser beam combining simulation experiment system was built to verify the feasibility and working effect of the design scheme.Finally,the beam combining accuracy of the actual beam combining system is tested,and the beam combining error is analyzed.The details are as follows :1.The overall design of the beam combining system is carried out.The beam combining method,beam combining components,beam combining scheme and the process of periodic closed-loop control are determined.The beam control model of the beam combining system is established,and the function relationship between the control quantity of the beam pointing adjustment device and the beam pointing deviation is obtained.The quantitative relationship between the control quantity of the beam position adjustment device and the beam position deviation is quantitatively analyzed.It is concluded that the control quantity of the position adjustment device is approximately equal to the position deviation of the system output beam.2.The laser beam monitoring device is designed,which mainly includes the beam pointing monitoring device and the beam position monitoring device.Firstly,the monitoring method,the selection of photodetector and the extraction algorithm of spot position are introduced.Then,according to the design requirements of the monitoring device,the Zemax optical design software was used to complete the detailed design of the 1000 mm focal length double-glue optical system and the 15 shrinking optical system optical system of the position monitoring device,and the chromatic aberration of the optical system was optimized.Then,according to the designed optical system,the structural design of the monitoring device is carried out,including the design of the arrangement of the optical path pointing to the monitoring device and the assembly of the device lens barrel.3.The beam adjustment device is designed,which mainly includes left and right position adjustment device,high and low position adjustment device and beam pointing adjustment device.The left and right position adjustment device uses a screw nut type electric translation stage to drive a single mirror fixed at an angle of 45 ° with the translation stage to realize the position adjustment of the outgoing beam along the left and right directions.The high and low position adjustment device adopts the design of the upper and lower two turning optical path to ensure that the height of the beam reference center is unchanged,and the upper and lower turning mirrors are driven by the screw nut type electric translation platform to adjust the position of the output beam along the high and low directions.In the beam pointing adjustment device,a twodimensional steering mirror driven by a voice coil motor is used to accurately adjust the beam pointing.After completing the detailed design of each regulating device and precision machining,the operation accuracy of each regulating device was tested.The pitch error of the left and right position adjustment device is better than 2.2″,and the azimuth error is better than 3.3″.The pitch error of the high and low position adjustment device is better than 2.8″,and the azimuth error is better than 4.0″.The pitch error of the two-dimensional steering mirror is better than 0.9″,and the azimuth error is better than 0.5″.4.Two visible light lasers with different wavelengths are selected to build a simulation experiment system of the beam combining device,and the feasibility of the designed periodic closed-loop beam combining correction scheme is verified.The results show that the designed correction scheme is reasonable and feasible.The beam combining accuracy of the beam combining system is tested.The static beam combining accuracy of the beam combining system for stable beam is : pointing accuracy 6.17μrad,position accuracy 0.66mm;the combination accuracy of three slow drift beams with different wavelengths is as follows: the pointing accuracy of wavelength 1 beam is 13.80μrad,and the position accuracy is 0.77mm;the pointing accuracy of the wavelength 2 beam is 17.25μrad,and the position accuracy is 0.84 mm.The pointing accuracy of the wavelength 3 beam is 17.25μrad and the position accuracy is 0.77 mm.In terms of beam combining efficiency,the beam combining efficiency of the three lasers is greater than 85%,which meets the requirements of the design index.Finally,the main error sources of the beam combining system are analyzed,and the method to improve the beam combining accuracy of the beam combining system is proposed. |
PDF Full Text Request