Research On Temporal Imaging Based On The Correlation Of Thermal Light

Correlated imaging is a novel imaging technique that obtains images of object based on intensity fluctuation correlation of thermal light.Temporal signal will distort when transmitting in a dispersion medium.In this paper,the study of temporal imaging is carried out by introducing first-order field correlation of thermal light and intensity correlation measurement into the time domain.Then the space-time duality between paraxial diffraction and pulse dispersion is analyzed from the perspective of wave equation.First-order temporal imaging and second-order Talbot self-imaging in the time domain of thermal light correlation are studied based on space-time duality.In the first chapter,we introduce the research background and the significance of the topic.In the second chapter,field correlation of thermal light and correlation imaging are introduced.In the third chapter,we first obtain the relationship between propagating of thermal light and impulse response function by comparing the wave equations of paraxial diffraction and pulse dispersion.Then the temporal impulse response functions of several typical optical systems are obtained.A temporal imaging scheme about first-order correlation of thermal light is designed,and the intensity expression describing this temporal imaging is obtained based on space-time duality.The results show that as the pulse width of the thermal light increases,the visibility of the temporal imaging decreases,while the square wave of the temporal object appears;When the coherence time of thermal light increases,the resolution of the temporal imaging decreases while the visibility increases.Therefore,to achieve the desired imaging which considered both the visibility and the resolution,it is necessary to choose the pulse width and coherence time of the thermal light appropriately.This result is of great significance for extending the method of correlation measurement to realize the reconstruction of temporal signals.In the fourth chapter,we design a scheme which can realize second-order Talbot self-imaging in the time domain based on intensity correlation of thermal light and carry out corresponding theoretical analysis.It is shown that the self-imaging of periodic temporal signals can be achieved based on this scheme while satisfying the Talbot condition and without additional dispersion compensation or cancellation.It is also possible to amplify or compress the temporal period signal.This provides a new theoretical support and technical path for the reproduction of periodic signals in a dispersive medium or the multiplication of frequencies.