Formation Mechanism Study Of The Light Spot On The Focal Plane Of Transmission Optical System

The quality of the light spot in the focal plane of imaging system is an important indicator to evaluate system performance.With the advantages of simple structure and large field of view,the transmission optical system is widely used in the practical application of detection,microscope,telescope,etc.However so far,the scattering light distribution on the focal plane of transmission optical system is rarely reported because the study of surface scattering is mainly focused on the surface scattering of the material surface.Formation mechanism of the light spot on the focal plane of transmission optical system is studied through experiments and ASAP ray tracing method.The researchresults are listed as follow:1.The distribution of light intensity in focal plane of transmission optical system is studied.Based on the Harvey BSDF scattering theory,a theoretical model of the firstorder surface scattering light in the optical transmission system is derived,which shows a Gaussian distribution law in the condition of small angle scattering.The theoretical model here agrees well with the experimental data.2.The focal plane imaging characteristics of the transmission optical system are studied.The surface scattering light spots of the transmission optical system includea kind of uniform circular bright spot focusing on the center of the focal spot of the laser imaging focus and ghost image areas which show annular spots.3.The source of stray light in the transmission optical system and the formation mechanism of the focal spot is studied.First-order scatter lights cause the main spot on the focal plane,and the ghost image by two reflections is the root cause of the other annular spots.4.The influence of optical parameters on imaging features of ghost images is studied by simulation.The intensity of Ghost image increases as the increase of surface reflectivity of the ghost devices with linearly;Changing ghost sphere radius will affect ghost image illumination and spot distribution;Tilting ghost device,transmission light focus position unchanged,ghost position has been significantly offset,what’s more,may be out of the visual field.Finding out the ghost device and adjusting parameters of the ghost device will be important ways of improving design and imaging quality of the transmission optical system.