| Since holography was proposed in 1940 s,it has been developed for more than 70 years.Compared with traditional optical imaging systems,holography can not only record the amplitude information of the object,but also the phase information of the object,so it can realize the object Three-dimensional recording.With the continuous advancement of modern electronic computing and optoelectronic components,people have proposed digital holography on the basis of holography.The recording and processing of digital holography is based on photoelectric coupling devices(CCD)and computer systems.Compared with traditional optical holography,digital holography makes the recording,storage,processing and reconstruction of holograms more convenient and accurate,and greatly improves the quality of imaging.Compared with other general imaging techniques,digital holography can achieve non-contact measurement imaging,and because it does not require imaging lenses,various aberrations are inherently reduced.Due to the above various advantages,digital holography is widely used in various imaging and measurement fields.On the basis of digital holography,a technology called phase-shift digital holography has been further developed.By collecting multiple holograms with phase shift values,the complex amplitude distribution of the object wave on the recording plane can be directly restored by the reconstruction formula.Compared with the traditional digital holography,the interference of zero-order term and conjugate term are avoided in the reconstruction process.Firstly,we introduce digital holography and phase-shift digital holography,and on this basis,the methods of phase-shift value extraction and object reconstruction of generalized phase-shift digital holography are introduced.Then,by changing the optical settings to achieve different reference light phase modulations,and respectively achieve slightly tilt reference and spherical reference,and perform spectrum analysis and wavefront reconstruction of digital holograms in both cases.In the case of slightly tilted reference light,special algorithms are combined to improve imaging efficiency.In the case of spherical wave reference light,the resolution of the imaging view is increased and the spatial recording field of view is increased while eliminating the error produced by collimating lens in the system.Finally,we analyze and compare the obtained results through computer simulations and experiments,and verifies the theory proposed before. |
