Research On High Dynamic Range Image Preprocessing Method For Hartmann Wavefront Sensor

Hartmann wavefront sensor has important applications in astronomical observation,laser beam purification,optical component detection,eye aberration detection and other scenes.It has a series of advantages such as simple structure,high energy utilization,strong adaptability to the environment,good real-time performance and so on.In the face of different complex application scenarios,the improvement of Hartmann wavefront sensor is also going deep.In the actual detection scenes,the nonuniform spatial distribution of the laser beam’intensity to be measured is unavoidable,especially when the laser beam output power is large or the laser beam is transmitted over a long distance in the atmosphere.Restricted by the existing photoelectric detector limited photosensitive dynamic range,when the near-field intensity distribution of the input sensor is very nonuniform,the spot array image collected by the photodetector of Hartmann wavefront sensor under single exposure will have obvious strong and weak distribution,and even appear complex conditions such as overexposure of spot,pixel loss and even spot loss..The inaccurate recording of the spot image information will significantly affect the accuracy of sub-aperture slope extraction and full-aperture wavefront detection of Hartmann wavefront sensor.The above problems are mainly caused by the fact that the dynamic range of the Hartmann wavefront sensor photodetector cannot match the intensity fluctuation of the near-field light beam.In the field of image processing,the problem of insufficient dynamic range to photodetectors,namely cameras,is also very common.For this reason,technicians have invented a variety of high dynamic range image processing technologies to solve the problem of limited dynamic range for cameras during photography.Inspired by this,the paper proposes that using high dynamic range image generation method to process the light spot array image of the Hartmann wavefront sensor,and obtain the light spot array image in the high dynamic range.In this paper,the influence of the nonuniform distribution of near-field light intensity on the detection accuracy of Hartmann wavefront sensor is analyzed.Then,through the simulation of conventional dynamic range spot array image,the influence of light intensity fluctuation,photodetector response function and dynamic range on the detection accuracy of the wavefront sensor is analyzed.Moreover,two images are used to generate high dynamic range spot array images,and the wavefront restoration errors corresponding to different methods are analyzed and compared,,which verifies the feasibility and effectiveness of high-dynamic range image preprocessing method of Hartmann wavefront sensor.It can provide a valuable technique for high-precision wavefront measurement of Hartmann wavefront sensor in the field with nonuniform intensity distribution.