Key Technologies Research Of Optics' Damage Online Detection In High Power Laser Facility

Laser-driven nuclear fusion is one of the important solutions to solve the energy issues.In the process of laser-driven nuclear fusion,high-power lasers will induce non-linear effects in optical components,which can degrade the beam quality and cause damages on optical components.Damage detection of optical component is necessary to keep the high-power solid laser facility operating safely.For online detection,the image of damages is acquired by imaging system.The damages of the detected component are analyzed by the image.The online detection is supposed to identify the damage spot with 50?m diameter.Once the diameter of initial damage reaches 50?m,the damage will develop rapidly according to related researches.Therefore,it takes 50?m diameter as the starting point.In high-power solid laser facility,KDP / DKDP crystal as a multiplier crystal will be damaged easily under the influence of multi-wavelength.For online detection,the damage on front or rear surface can be confirmed by the different growth characteristics indirectly.At present,the indirect method is used both at home and abroad.In this paper,the birefringence of DKDP crystal is used to confirm the damage on the front or rear surface by polarization modulation imaging.Compared with the current identification methods,it has the advantages of high accuracy and high efficiency.The online detection for large diameter optical components,limited by the working distance and the resolution of the detector,can't identify 50?m damage by optical means directly.Therefore,the radiation calibration is used to achieve the recognition effect.In this paper,a series researches have been carried out on uniform illumination,the damage identification on front and rear surface of DKDP crystal,radiation calibration of micro-damage:1.Based on the principle of online detection,the signal-to-noise ratio formula of damaged image under multi-damages and multi-components is deduced,which provides theoretical support for the design of detection system.2.The edge and angle illumination is simulated,and the configuration scheme of lighting have been determined.Encode the optical components in spatial,and encode the lighting sources in time at the same time.In this way,the optical component to which the damage belongs can be confirmed.3.The conditions of Rayleigh scattering is analyzed on DKDP crystal.The light scattering is geometry scattering on the 50?m damage.The o-light and e-light caused by birefringence of DKDP crystal will produce their own imaging,which will make great influence on damage identification and radiation calibration.The birefringence of DKDP crystal can be used to confirm to which surface the damage belongs.The experiments is completed.4.The principle of radiation calibration is studied,and four curves under four different conditions are acquired after the effect of birefringence eliminated.The radiation calibration is feasible through the four curves.The method can identify the 50?m damage through experiments,which enriches data of the radiation calibration.