Study On Optics Damage Online Inspection Based On Plenoptic Camera

In high power laser,optics damage will result in different degrees of scattering and diffraction,which will lead to performance degradation of optical system.When the power of laser is high enough,the optics will be damaged that will influence the whole optical system.Therefore,optics damage online detection and location is required to reduce the risk to equipment due to an implosion of optics damage,to provide the ability to remove optics before they are damaged beyond repair and to reduce the performance degradation of the laser.However,at present,the images of the optics will be overlapped each other in the online inspection method,and to locate the optics,we must focus the damage in turn.Besides,it's difficult to discriminate which optics the damage occur when two or more optics are in close proximity.For the complex optical system,this will result in performance degradation of efficiency and effectiveness when completing a online inspection.To overcome these problem,in this thesis,the single lens 3D imaging camera(plenoptic camera)is introduced in the optics damage online detection and location method.Firstly,to different optical systems,the physical parameters of plenoptic camera should be designed properly,so that the field of depth,the depth resolution and the spatial resolution of the plenoptic camera will be applicable to the corresponding optical system.Hence,in this thesis,we summarized and derived the quantitative relationship between the performance parameters and physical parameters of plenoptic camera from the standpoint of geometric optics according to the previous research in the history,which can be a guidebook for plenoptic camera design.What's more,to reveal more truth of plenoptic camera imaging with small diameter microlens,we re-described and simulated the imaging process of the plenoptic camera from the standpoint of physical optics.Secondly,in general,the optical path is long and narrow in the optical system(the length of the optical path is about several meters to tens of meters and the aperture is about several millimeters to hundreds of millimeters),so the field of depth of plenoptic camera should be large enough when using it in online detection.At present,to extend the field of depth,multi-focus microlens array is applied in plenoptic camera.Besides,with the development of plenoptic camera,irregular arrangement microlens array may also be applied in plenoptic camera.It is a challenge to the available calibration methods.For this problem,an automatic calibration method based on digital morphology is proposed in this thesis.Finally,the plenoptic camera is calibrated without prior knowledge of microlens array parameters,which improves the robust and intelligence of plenoptic camera.Thirdly,to verify the on-line inspection method based on plenoptic camera,the principle experiment is done in this thesis.Specifically,we built a simulating optical system firstly,and then design and built the experimental prototype of the plenoptic camera.Subsequently,the raw image processing methods(such as damage extraction and matching algorithm,depth estimation algorithm and pseudo-color depth map)are coded,and the depth map of damage is achieved finally.All in all,in this thesis,the optics damage on-line detection and location method based on plenoptic camera is proposed.Concretely,the imaging laws of plenoptic camera from the standpoint of physical optics are derived,an automatic calibration method is proposed,and the related algorithms of plenoptic camera application are realized.At the same time,the application scope of plenoptic camera is extended.