Study On A Hartmann Wavefront Sensor With Adjustable Spatial Sampling Rate

In astronomical adaptive optics,the observation condition is constantly changing.Hartmann wavefront sensor of high pupil sampling has a higher measurement accuracy under good observation conditions.when the observation condition is poor,only Hartmann wavefront sensor of low pupil sampling can measure the target object effectively.However,there are not many methods to adjust pupil sampling with classic Hartmann wavefront sensor,and all current methods have some shortcomings.Classic Hartmann wavefront sensor is calibrated with plane waves,which is not conducive to adjust pupil sampling.In this paper,Hartmann wavefront sensor calibrated with spherical wave(spherical Hartmann sensor)is studied,and a method to adjust pupil sampling is proposed.In this paper,the details of adjusting pupil sampling based on spherical Hartmann sensor are discussed,and the influence of variable pupil sampling on the main performance parameters of spherical Hartmann sensor is analyzed.Based on the angular spectrum theory of light wave propagation,the MATLAB numerical simulation of spherical Hartmann sensor is established.And the performance of spherical Hartmann sensor is discussed by the MATLAB numerical simulation.Finally,a simple experimental platform of spherical Hartmann sensor is built in this work.With the platform,the measurement of adjustable pupil sampling by spherical Hartmann sensor is conducted under both strong light environment and low light environment.Under the strong light environment,the absolute measurement accuracy(RMS of the residual)of spherical Hartmann sensor is better than 1/25?(?=635nm),and the relative measurement accuracy(relative RMS of the residual)is below 9%.Under the low light environment,the measurement accuracy of spherical Hartmann sensor is improved by reducing the pupil sampling.It is verified that spherical Hartmann sensor with adjustable pupil sampling has better adaptability to different observation conditions.