Phase Diversity Based Adaptive Imaging By Incoherent Digital Holography

Fresnel incoherent correlation holography(FINCH)is a non-scanning three-dimensional imaging technique.In FINCH,the object is illuminated by spatial incoherent light source.The lights emitted from any two different points are mutual incoherent.However,the hologram of a point light source can be achieved by splitting the light from the point source into two beams.They can be recorded by capturing the interference pattern generated by two beams that originated from the same point.The hologram of an extended object is the incoherent superposition of all the points' holograms.The hologram contains 3D position information of every points.So 3D object can be reconstructed combined with proper algorithms.Incoherent holography enables the non-scanning three-dimensional imaging of spatial incoherent samples and holds great potential in various of practical applications.In recent years,the researches about incoherent are focused on the improvements of imaging performances such as imaging speed and resolution.In this paper,the imaging performance of incoherent holography is improved by combing adaptive optics techniques.Adaptive optics techniques can achieve detecting and correcting the optical aberrations induced during the imaging of the sample.Here we demonstrate the basic principle of incoherent digital holography.The theoretical model of wavefront sensing mechanism of incoherent holography is demonstrated.Consequently,wavefront correction and adaptive imaging is achieved combing with incoherent holographic imaging characteristics.Based on phase diversity technique,wavefront sensing and aberration correction are achieved.The detail performances such as the choosing of diversity and metric function are analyzed.The effects of the choosing of metric function on the estimation of optical aberrations and the quality of reconstructed image are simulated.The effect of Wiener filter coefficients on the quality of reconstructed image is also analyzed.Optical setup of incoherent holographic system is built.We developed two different kinds of phase-diversity-based incoherent holographic adaptive imaging method: 1)the aberrations are estimated based on phase diversity,and then corrected using spatial light modulator;2)the aberrations are estimated based on phase diversity,and then corrected directly in numerical algorithm.Experiments also are researched.The imaging performances of above two cases are discussed.The experimental results demonstrated that the optical aberrations can be detected and corrected efficiently using the proposed phase-diversity-based incoherent holographic adaptive imaging method.Our method can use less data to adaptive imaging to improve reconstruction quality and imaging resolution.