Vector 3D Display Based On Pixelated Blazed Gratings

Autostereoscopic 3D display expresses the light field information of an object by projecting multiple parallax images within narrow observation zones.Under the condition of limited refreshable data,it is considered as the most promising glasses-free 3D display technology for commercialization.Autostereoscopic 3D display based on geometric optics is limited by the weak light control capabilities,which lead to visual fatigue and crosstalk.Vector 3D display proposed by our group manipulate the directions of propagating light beams pixel by pixel,which significant reduced ghost images.However,the diffraction efficiency of the binary nanograting is low with a theoretical limit of 40%.For this reason,this paper employs laser direct writing technology and grayscale lithography to prepare multi-step binary optical elements for vector 3D display,which greatly improves the light efficiency.The main research works of this paper are as follows:(1)This paper introduces the design of diffractive optical elements and harmonic diffractive elements.We studied the diffraction efficiency and dispersion characteristics of diffractive optical elements and harmonious diffractive elements.We also analyzed the impact of period error,phase height error,and ring-band transition region error on diffraction efficiency.(2)Vector 3D display based on a multi-step Fresnel zone plate array is proposed in this paper.Laser direct writing lithography is used to develop a pixelated 4-step Fresnel zone plate.The experimental results showed that the diffraction efficiency of the 4-step Fresnel zone plate reaches 60%(theoretical value is 80.5%).A plurality of 4-step Fresnel zone plates were separated and recombined to form a viewing modulator.The view modulator is integrated with the shadow masks to achieve static 3D display.The resolution of each viewing angle is 200×200,with a viewing angle of 12°.(3)This paper analyzed the design and fabrication method of the harmonic diffraction lens.We further proposed vector 3D display based on the harmonic diffraction blazed grating.Grayscale lithography system is used to fabricate the view modulator based on the harmonic diffraction blazed grating.The view modulator was aligned with the off-the-shelf LCD panel for full-color dynamic 3D display.The resolution of each viewing angle is 568×320,with a viewing angle of 12°.The diffraction efficiency of the harmonic diffraction lens reached 82%(theoretical value is 99.9%).