Research Of Jones Matrix Measurement Based On Four-channel Digital Holography

Digital holography is a measuring method that combines optical holography and digital picture processing technique.Digital holography method records hologram with CCD instead of holographic plate,and reconstructs image with a computer instead of optical operation.Therefore,digital holography has advantages of high efficiency,real-time and convenience that traditional optical holography does not have.Nowadays,digital holography has been widely used in many fields,such as transmissivity measurement of objects.As for objects with anisotropy,due to the polarization response characteristic,we often completely describe their transmission properties by Jones matrix.Because Jones matrix includes four elements,we have to use multiple channels for measurement to keep the advantages of digital holography.The existing methods of digital holography include two-channel and four-channel measurements.However,neither of them is practical for Jones matrix measuring because of their unreliability of real-time measurement and complicating device.Therefore,it is urgent to find a real-time,simple and fast Jones matrix measuring method.In this dissertation,we propose a digital holography Jones matrix measuring method by using single laser and single shot based on the existing dual-channel and four-channel digital holography.In this scheme,Jones matrix of a dynamic object can be measured by a single shot.Moreover,the optical system is simplified to a great extent because it requires only one single laser.Finally yet importantly,this system can be directly improved by a dual-channel system.which makes it easy to be built.Due to these advantages,this scheme has certain superiority in transmittance property measuring of the anisotropic objects compared with previous methods.Using the proposed method,we have measured the Jones matrix of twisted nematic liquid-crystal spatial light modulator(TN-LCSLM)which loads different gray scale.We find the modulation characteristic curve between the gray scale and amplitude modulation,and then give explanation in the dissertation.Based on the characteristic curve,we can experimentally adjust the figures loaded on TN-LCSLM for better amplitude modulation result.Compared with traditional measuring method,the new proposed four-channel digital holography can reduce the operating time to 1/8 but keep high accuracy,making it much more convenient in modulation curve measuring.