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集成成像3D显示模式可以分为实模式、虚模式和聚焦模式三种。在实模式的集成成像3D显示中,3D图像是凸出显示屏的;在虚模式的集成成像3D显示中,3D图像是凹进显示屏的;基于线光源的集成成像3D显示处于聚焦模式,它可以在显示屏的两侧分别成3D像。因此,基于线光源的集成成像3D显示具有较强的深度感。如图1所示,基于传统线光源的集成成像3D显示的主视区是微图像阵列中所有图像元的成像区域的公共部分。基于传统线光源的集成成像3D显示器的观看视角θ和亮度L为[10, 12]:
图 1 基于传统线光源的集成成像3D显示器参数图
Figure 1. Parameter of the integral imaging 3D display based on a conventional line light source
$$\theta = 2\arctan \left[ {\frac{{p - w}}{{2g}} - \frac{{\left( {m - 2} \right)p}}{{2l}}} \right]$$ (1) $$L = \frac{{Cw}}{p}$$ (2) 式中:p为图像元的节距;w为线光源的宽度;m为微图像阵列中图像元的数目;g为线光源与图像元的间距;l为观看距离;C为2D显示时的亮度。由公式(1)可知,在基于传统线光源的集成成像3D显示中,3D图像的观看视角与线光源的节距成正比,与线光源的宽度成反比。由公式(2)可知,在基于传统线光源的集成成像3D显示中,3D图像的亮度与线光源的节距成反比,与线光源的宽度成正比。因此,虽然可以通过减小线光源的节距或增大线光源的宽度来增大3D图像的亮度,但是会降低3D图像的观看视角。
文中提出的高亮度集成成像3D显示器包括有机电致发光(Organic Light Emitting Diode, OLED)显示屏和液晶显示屏,如图2所示。OLED显示屏平行放置于液晶显示屏后方,且对应对齐。OLED显示屏用于生成渐变线光源,液晶显示屏用于显示微图像阵列。
图 2 基于渐变线光源的集成成像3D显示器结构图
Figure 2. Structure diagram of the integral imaging 3D display based on a gradient line light source
如图3所示,渐变线光源中线光源的数目等于微图像阵列中图像元的数目。渐变线光源中线光源的节距等于微图像阵列中图像元的节距。每个线光源的中心均与对应图像元的中心对应对齐。每个线光源发出的光线均照亮与其对应的图像元,在观看视区内重建3D像素。
图 3 基于渐变线光源的集成成像3D显示器的原理和参数图
Figure 3. Principle and parameter of the integral imaging 3D display based on a gradient line light source
与传统线光源不同,渐变线光源中线光源的宽度从两边向中心逐渐增大。因此,微图像阵列中图像元的成像区域宽度从中心向两边逐渐增大。通过合理设置渐变线光源左半部分线光源的宽度,可以使得位于显示屏左半部分的图像元成像区域的右边缘均重合。通过合理设置渐变线光源右半部分线光源的宽度,可以使得位于显示屏右半部分的图像元成像区域的左边缘均重合。即:基于渐变线光源的集成成像3D显示的主视区是位于微图像阵列中心的两个图像元成像区域的公共部分。由图3可知,渐变线光源中第i列线光源的宽度Hi为:
$$\left\{ \begin{array}{l} {H_i} = {H_1} + \dfrac{{2gp}}{l}\left( {\dfrac{m}{2} - i} \right)\;\;\;\;\;\;\;\;\;\;1 \leqslant i \leqslant \dfrac{m}{2} \\ {H_i} = {H_1} + \dfrac{{2gp}}{l}\left( {i - \dfrac{m}{2} - 1} \right)\;\;\;\;\;\dfrac{m}{2} < i \leqslant m \\ \end{array} \right.$$ (3) 式中:H1为渐变线光源中第一列线光源的宽度。由图2可得,基于渐变线光源的集成成像3D显示器的观看视区宽度D为:
$$D = \frac{{\left( {p - {H_1}} \right)l}}{g} - \left( {m - 2} \right)p$$ (4) 基于渐变线光源的集成成像3D显示器的观看视角θ′和亮度L′为:
$$\theta ' = 2\arctan \left[ {\frac{{p - {H_1}}}{{2g}} - \frac{{\left( {m - 2} \right)p}}{{2l}}} \right]$$ (5) $$L' = \sum\limits_{i = 1}^m {\frac{{C{H_i}}}{{mp}}} $$ (6) 式中:Hi为渐变线光源中第i列线光源的宽度。
由公式(5)和(6)可知,与基于传统线光源的集成成像3D显示器相同,文中提出的集成成像3D显示器的亮度与渐变线光源中所有线光源的宽度成正比;与基于传统线光源的集成成像3D显示器不同,文中提出的集成成像3D显示器的观看视角仅与渐变线光源中第一列线光源的宽度成反比。渐变线光源中线光源的宽度从两边向中心逐渐增大,因此可以在保持观看视角的前提下显著增大3D图像的亮度。更进一步地,可以根据实际需求,合理设置渐变线光源中第一列线光源的宽度,同时实现宽视角和高亮度集成成像3D显示。
High luminance integral imaging 3D display based on gradient line light source
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摘要: 为了解决观看视角与亮度的相互制约关系,设计了一种基于渐变线光源的集成成像3D显示器,通过设置渐变线光源中每列线光源的宽度,优化微图像阵列中每列图像元的成像光路,建立了3D成像模型,通过几何光学推导了观看视角以及亮度的计算公式;研制了基于渐变线光源的集成成像3D显示实验装置,通过实验验证了可以在保持观看视角的前提下将3D图像的亮度提高为传统集成成像3D显示的4.5倍。Abstract: To resolve mutual restriction of viewing angle and luminance, a high luminance integral imaging display based on a gradient line light source was proposed. The light paths of the elemental images in the element image array were optimized by adjusting the widthes of the line light sources in the gradient line light source. The imaging model of the integral imaging display based on the gradient line light source was established. The calculation formulas of the viewing angle and luminance were obtained by using geometrical optics. An experimental apparatus of the integral imaging display based on the gradient line light source was built. The experimental results prove that the luminance of the 3D image is 4.5 times of the conventional one without loss of the viewing angle.
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Key words:
- integral imaging /
- gradient line light source /
- viewing angle /
- luminance
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[1] Wang Tonghao, Liu Bingqi, Huang Fuyu, et al. Reasonable benefit value of the parameters of the parallel infrared binocular stereo system [J]. Infrared and Laser Engineering, 2017, 46(9): 0904004. (in Chinese) [2] 王琼华. 3D显示技术与器件[M]. 北京: 科学出版社, 2011: 203-206. Wang Qionghua. 3D Display Technology and Device[M]. Beijing: Science Press, 2011: 203-206. (in Chinese) [3] Zhang Hanle, Deng Huan, Ren Hui, et al. Method to eliminate pseudoscopic issue in an integral imaging 3D display by using a transmissive mirror device and light filter [J]. Optics Letters, 2020, 45(2): 351-354. doi: 10.1364/OL.45.000351 [4] Ma Shitu, Lou Yimin, Hu Juanmei, et al. Enhancing integral imaging performance using time-multiplexed convergent backlight [J]. Applied Optics, 2020, 59(10): 3165-3173. doi: 10.1364/AO.385768 [5] Zhang Wanlu, Sang Xinzhu, Gao Xin, et al. A flipping-free 3D integral imaging display using a twice-imaging lens array [J]. Optics Express, 2019, 27(22): 32810-32822. doi: 10.1364/OE.27.032810 [6] Li Henan, Wang Shigang, Zhao Yan, et al. 3D view image reconstruction in computational integral imaging using scale invariant feature transform and patch matching [J]. Optics Express, 2019, 27(17): 24207-24222. doi: 10.1364/OE.27.024207 [7] Yan Zhiqiang, Yan Xingpeng, Jiang Xiaoyu, et al. Computational integral imaging reconstruction of perspective and orthographic view images by common patches analysis [J]. Optics Express, 2017, 25(18): 21887-21900. doi: 10.1364/OE.25.021887 [8] Wu Fei, Zhao Baichuan, Liu Zesheng, et al. Dual-view integral imaging display using a polarizer [J]. Applied Optics, 2020, 59(19): 5785-5787. doi: 10.1364/AO.394532 [9] Wang Qionghua, Ji Chaochao, Li Lei, et al. Dual-view integral imaging 3D display by using orthogonal polarizer array and polarization switcher [J]. Optics Express, 2016, 24(1): 9-16. doi: 10.1364/OE.24.000009 [10] Kim Y, Kim J, Kim Y, et al. Thin-type integral imaging method with an organic light emitting diode panel [J]. Applied Optics, 2008, 47(27): 4927-4934. doi: 10.1364/AO.47.004927 [11] Deng Huan, Wang Qionghua, Wu Fei, et al. Cross-talk-free integral imaging three-dimensional display based on a pyramid pinhole array [J]. Photonics Research, 2015, 3(4): 173-176. doi: 10.1364/PRJ.3.000173 [12] Fan Jun, Wu Fei, Lv Guojiao, et al. Integral imaging 3D display based on variable-aperture pinhole array [J]. Infrared and Laser Engineering, 2018, 47(6): 0603005. (in Chinese)