Correlation Research Of Wide Spectrum Scattered Light Field

Optical imaging through scattering media is an important research direction in optical imaging.It plays an important role in fire rescue,traffic,biological imagingand so on.At present,the methods of imaging through scattering media mainly include adaptive optics,wavefront shaping,speckle autocorrelation and so on.However,most of these methods only consider the case of monochromatic illumination and two-dimensional object imaging,which is difficult to meet the actual needs.In order to realize practical applications of imaging through scattering media,vases for wide spectrum illumination and three-dimension objects must be considered.Aiming at the above two problems,combined with the imaging principle of optical memory effect,we introduce a phase plate model,and discuss the correlation of speckle fields generated by different wavelengths and sources at different longitudinal distances.At the same time,models related to the incident angle are established,and the field of view of optical memory effect is simulated in the numerical simulation based on this model.The specific work is as follows:(1)Because the phase screen model can not reflect the wavelength difference and simulate the case of wide-spectrum illumination,we propose phase plate model in this paper.Based on the phase plate model,we obtain the wide-spectrum speckle pattern in numerical simulation,and analyze the morphology and statistical characteristics of wide-spectrum speckle pattern.In addition,we also analyze the correlation of speckle fields under different thicknesses and central wavelengths through numerical simulation.(2)Based on the phase plate model,the correlation(or second-order coherence)of speckle fields generated by light sources at different longitudinal positions is analyzed theoretically.It is found that the variation of the effective angle of the light source determines the correlation of the speckle field at different longitudinal distances,and the theoretical results are displayed by numerical simulation.In addition,we also use the point spread function at a fixed distance to recover objects at different longitudinal distances,the theoretical results are verified again from the perspective of imaging.(3)Aiming at the problem that the phase plate model can not reflect the field of view of optical memory effect,two models related to incident angle are proposed in this paper.Based on this model,we simulate the field of view of optical memory effect and estimate the effective thickness.At the same time,imaging of multispectral objects within the memory effect range is realized using the wavelength dependent characteristics of the phase plate model.