Research On Correlated Imaging And Second-order Orbital Angular Momentum Correlation With Pseudo-Thermal Light

Lensless ghost imaging has attracted much interest in recent years due to its profound physics and potential applications.In the lensless ghost imaging system,a pseudo-thermal light is split into two correlated beams by a beam splitter.One beam goes to a chargecoupled detector camera,labeled as CCD2.The other beam goes to an object and then is collected in another charge-coupled detector camera,labeled as CCD1,which serves as a bucket detector.We report studies of the robust properties of the lensless ghost imaging system with a pseudo-thermal light source in a strongly scattering medium.The effects of the positions of the strong medium on the ghost imaging are investigated.When the strong medium,a pane of ground glass disk,is placed between the object and CCD1,the bucket detector,the quality of ghost imaging is barely affected and a good image could still be obtained.The quality of the ghost imaging can also be maintained,even when the ground glass is rotating,which is the strongest scattering medium so far.However,when the strongly scattering medium is present in the optical path from the light source to CCD2 or the object,the lensless ghost imaging system hardly retrieves the image of the object.A theoretical analysis in terms of the second-order correlation function is also provided.Photons that are entangled or correlated in orbital angular momentum have been extensively used for remote sensing,object identification and imaging.It has recently been demonstrated that intensity fluctuations give rise to the formation of correlations in the orbital angular momentum components and angular positions of random light.Here,we demonstrate that the spatial signatures and phase information of an object,with rotational symmetries,can be identified using classical orbital angular momentum correlations in random light.The Fourier components imprinted in the digital spiral spectrum of the object,measured through intensity correlations,unveil its spatial and phase information.Sharing similarities with conventional compressive sensing protocols that exploit sparsity to reduce the number of measurements required to reconstruct a signal,our technique allows sensing of an object with fewer measurements than other schemes that use pixel-by-pixel imaging.One remarkable advantage of our technique is the fact that it does not require the preparation of fragile quantum states of light and works at both low-and high-light levels.In addition,our technique is robust againstenvironmental noise,a fundamental feature of any realistic scheme for remote sensing.We propose and perform an interference experiment involving a distributed angular double-slit and the orbital angular momentum(OAM)correlations of thermal light.In the experiment,two spatially separated angular apertures are placed in two correlated light beams generated by splitting the thermal light beam via a beam splitter.The superposition of the two spatially separated slits constitutes an angular double-slit in two-photon measurements.The angular interference pattern of the distributed double-slit is measured even though each beam interacts with a different part of the object.This scheme allows us to discriminate among different angular amplitude objects using a classical incoherent light source.This procedure has potential applications in remote sensing or optical metrology in the OAM domain.