Coherent Properties Of Liquid Crystal Spatial Light Modulator And Its Applications In Digital Diffractive Optics

With the development of computer technology, high resolving digital image sensor(CCD or CMOS) and high resolving digital spatial light modulator (LCD, LCOS, DMD),digital, real-time and dynamic devices are widely used in the field of wavefrontmeasurement and transform. For example, the wavefron transform can be accomplisheddynamically by use of Computer Generated Holograms (CGH) or Diffractive OpticalElements (DOE) displayed on a Liquid Crystal Spatial Light Modulator (LCSLM). Anew research field, called digital diffractive optics, is emerging. In this thesis, we mainlyinvestigate the coherent properties of LCSLM and its application in digital diffractiveoptics. The main researches are as follows.(1).Based on the analysis of liquid crystal directors, we construct mathematic modelto extract the distribution of directors. Further we design a MATLAB program, by whichthe distribution of liquid crystal's director can be obtained through an iteration algorithm.The work described above forms the foundation for analyzing coherent properties anddiffraction properties of LCSLM.(2).Based on the theory of Jones matrix, we analyze complex-amplitude modulationproperties of TN-LCSLM in off-state and open state, respectively. Compared with the offstate, the open state is hardly analyzed theoretically. It is only described in numericalforms. Based on the parameters computed by MATLAB, the intensity transmittance inopen state is numerically computed. Besides the numerical computing, a feasible methodanalyzing TN-LCSLM's diffractive efficiency is proposed.(3).Given the computed parameters and Jones matrix, TN-LCSLM'scomplex-amplitude transmittance is analyzed. As an example, we analyze thediffraction efficiency (first order) of one dimensional rectangular grating displayed onTN-LCSLM. The analysis and computing results demonstrate that the diffractionefficiency is related to not only applied voltage but also the configuration of input andoutput polarizer even the orientation of axis. The existence of optimal diffractionefficiency is also found and ascertained.(4).Based on the wavefront aberration theory, we analyze the influence brought outby wavefront aberration. As an example here, we discuss influences of this kind ofaberrations on reconstructed results of Fourier digital holograms. We put forward a newmethod to alleviate the influence by means of shack-hartmann wavefront sensor and givebasic analysis. Analyses and simulations reveal that the method can effectively concealthe influence and improve the quality of image greatly.