| The technique of performing high efficiency wavefront measurement and adjustment based on integrating micro-nano-control-light and photo-sensitive function,which is realized through constructing a specific spatial deflection arrangement of liquid-crystal(LC)molecules driven by the spatial electric-field generated between both electrodes of a pre-shaped LC micro-cavity,is also a high-performance adaptive optical detection means,and thus developed rapidly in recent years.As shown,the electronically controlled LC micro-nano-control-light structures demonstrate an excellent development prospect because of its flexible control,stable and reliable control-light conversion,low power consumption,being easy to coupling and even integrating with other functional structures.In this thesis,the research of constructing a kind of electronically controlled liquid-crystal microlens matrix(ECLCMM)for improving wavefront measurement and regulation based on the electrically adjusted dielectric property of nematic LC materials,is carried out.The wavefront measurement and regulation capability is remarkably enhanced by the electronically tuning and swinging focus of the ECLCMM,in which a needed spatial distribution of LC directors is orderly constructed and further adjusted through the electric-field excited in preshaped LC layer with a typical micron-scale thickness.The main work of this thesis is as follows:Firstly,based on the LC continuum elastic principle and electromagnetic field theory,the finite difference iteration method is used to model the LC director distribution and spatial electric-field generated,and further simulate several classical LC microlenses for verifying the model constructed.Based on realizing LC microlenses with single circular-hole electrode and dual-semi-circular-hole electrode,an ECLCMM with sector-shaped annulus electrode,which can be used to conduct focus swinging on the focal plane and also the focus adjusting along the optical axis,is designed successfully.Simulations show that the operations including setting different circular-hole size and the aperture ratio of the circular-hole and electrode region will significantly affect the beam collecting and focusing of the ECLCMM for performing Shack-Hartmann(SH)wavefront measurement and regulation,such as a typical case of oversize circular-hole leading to sub-focusing.The optimized aperture ratio is: micro-aperture/sector-shaped external diameter = 2/3,and each micro-hole aperture of 10×10 array being 60?m,and the sector-shaped external diameter being 90?m.Secondly,an ECLCMM based on indium tin oxide(ITO)electrode materials is fabricated through technological process including common UV-photolithography,electron beam evaporation and overlaying process,and then the performances are tested.The typical parameters include: the focal length of 1.76 mm corresponding to the driving voltage signal of 4.95 Vrms,the focal length being shorter as the RMS voltage signal raising.In order to improve the control-light efficiency,another ECLCMM based on aluminum electrode with low resistivity and stray-light-shielded is further fabricated.The typical parameters include: efficiently achieving focusing in a driving voltage range of 3~7Vrms,and the focus being in a range of 2.00~0.60 mm,the maximum focus-swinging amplitude being 8?m,and the ratio of focusing swinging amplitude and focal length(SF)being ~8‰.Based on the principle of thin-film field effect transistors LC scanning,an "active matrix" of voltage signal scanning for driving ECLCMM is designed.The simulations and experimental tests of the control circuit system show that the drive voltage signal can reach up to a maximum value of ~10Vrms,so as to effectively meet the requirement of driving and controlling the ECLCMM developed by us,and thus lay a concrete foundation for further developing wavefront measurement and regulation technology based on functioned LC micro-nano-structures. |
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