Research On The Beam Homogenization System Based On The Microlens Arrays And Random Scenes

Microlens arrays have been widely applied in display,imaging,transmission,surveying and mapping and other fields due to their high optical filling factor and parallel imaging capability for the last decades.At present,many scholars and laboratories have studied the aperture,refractive index,arrangement and eccentricity of the sub-lens.And the development of microlens arrays processing technology is also mature enoughBecause of the advantages in transmission efficiency and uniformity,microlens arrays have been used more than other components in the field of beam homogenization.There are two kinds of array systems used for beam homogenization,which are called diffracting type and refracting type.Among them,when the refracting type is combined with the Kohler illumination system,the uniformity is better.Therefore,according to the theory of microlens arrays and the Kohler illumination,this thesis studies the beam homogenization system on the basis of general imaging systemFirstly,the beam homogenization model was derived from the paraxial optics.The theoretical model of beam homogenization system was obtained by adding microlens arrays and other components into the existing imaging system.In addition,the coordinates of light passing through the system were given by the formula derivation.According to the analysis,the spot size of the image plane is positively correlated with the focal length of the integration lens and the aperture of the sub-lens,and negatively correlated with the focal length of the sub-lens.Meanwhile,the light divergence angle of the image plane is positively correlated with the aperture of the sub-lens,and negatively correlated with the focal length of the integration lens and the sub-lens.Secondly,based on the parameters and requirements of an imaging system,the ray tracing method and scalar diffraction theory were used to simulate the beam homogenization system,respectively.In the process of ray tracing simulation,the actual lenses were designed and the sub-lens aperture was optimized.At the same time,the simulation based on the scalar diffraction theory was using the ideal system parameters.Finally,these two simulation results all verify the good uniformity of the system.Thirdly,the homogenization system was simulated with different scene pictures taking from life in the OTS.The actual lenses with focal length of 55mm,half field of view of 6.5° and F number of 1.93 were further optimized,then the imaging simulation and homogenization simulation were completed,respectively.According to the experimental results,the system achieved good uniformity for any scene source.Ultimately,the uniformity of the image plane could reach more than 95%.Simultaneously,compared with the imaging system,the energy efficiency of the beam homogenization system could reach more than 30%in the imaging field of view.Moreover,considering the influence of the light outside the imaging field of view,the energy efficiency of the beam homogenization system in the 10°field of view was also observed,which could reach more than 69%.