| The naked-eye 3D display using cylindrical lens grating technology is characterized by low brightness losses,easy realization of stereoscopic display,and simultaneous multi-person viewing.However,the cylindrical lens technology also has the disadvantages of serious crosstalk,and the stereoscopic display depth is not strong.Therefore a novel naked-eye 3D display panel structure was studied,which is composed of a free-form cylindrical lens grating array,a liquid crystal display screen,and a side-emitting optical fiber directional backlight.The backlight is composed of a cylindrical plano-convex lens array,a side light emitting fiber array,a lens coupler,and a white LED.The thesis mainly designs two free-form surface lenses for use in the novel naked-eye 3D display,aiming at solving the problem of large crosstalk of the traditional cylindrical lens type naked-eye 3D display.Design of the free-form cylindrical lens.The incident surface of the free-form cylindrical lens grating array is a concave free-form grating structure with the same number as the sub-pixel on the screen display panel,and the exit surface is an convex free-form slanted gratings structure.Design formulas for grating free-form surface and grating parameters are deduced based on the principles of naked-eye 3D display and geometrical optics.The grating array parameters are calculated using MATLAB and grating array model is established by modeling software Solid Works.Trace Pro performs ray tracing simulation on the designed grating array model.The results show that the image crosstalk in 6-view novel naked-eye 3D displays is 0.068% at the best viewing angle by selecting optimal parameters,which is lower than a traditional one by 2 orders of magnitude.The image crosstalk remains basically unchanged within the range of the viewing distance of 2000 mm ~ 3000 mm.Design of the free-form lens coupler.The side-emitting optical fiber array is similar to the ideal line source array.Place it at the focal plane of the cylindrical plano-convex lens array to emit a beam with a small divergence angle,which can well solve the problem that the divergence angle of the traditional LED backlight is too large.The free-form lens coupler is a device for coupling light energy between LED light source and side-emitting optical fiber arrays.The free-form lens coupler consists of two refractive free-form surface,two reflection free-form surface and a circular cylindrical lens surface.The small divergence angle of the modified Lambertian high-power LED beam is quasi-uniformly distributed on the end face of POFB through refractive free-form surface.The reflection free-form surface reallocate the energy of large divergence angle of LED beam as compensation to improve the target surface illumination uniformity.Lens coupler is designed and optimized for illumination uniformity and light use efficiency of the end face of the fiber bundle.The results of optical simulation show that when the 3535 LED is used as the light source,the designed coupler can make the illumination uniformity of the 20 × 20 polymer fiber bundle with the diameter of 0.5mm reach 92% and the light use efficiency reach 71%.At the end of the thesis,the free-form lens coupler is experimentally tested.The results show that the designed coupler can make the uniformity of the end face illumination of the POFB reach over 90%,which is basically consistent with the simulation results. |
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