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Crosstalk-free integral imaging 3D display using pinhole array
Optik - International Journal for Light and Electron Optics 184 (2019) 538–541
Contents lists available at ScienceDirect
Optik journal homepage: www.elsevier.com/locate/ijleo
Original research article
Crosstalk-free integral imaging 3D display using pinhole array Fei Wua,c, Guo-Jiao Lva, Bai-Chuan Zhaoa, Ze-Sheng Liua, Qiong-Hua Wangb,
⁎
T
a
School of Electronics Engineering, Chengdu Technological University, Chengdu, 611730, China School of Instrumentation Science and Opto-electronics Engineering, Beihang University, Beijing, 100191, China c School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, 610054, China b
A R T IC LE I N F O
ABS TRA CT
Keywords: Integral imaging Pinhole array Crosstalk Aperture width
We propose a crosstalk-free integral imaging three-dimensional (3D) display using a pinhole array. It consists of a back light unit, a pinhole array and a liquid crystal panel. The pinhole array, which is attached to the back light unit, is located between the back light unit and the liquid crystal panel. Three imaging models of the integral imaging 3D display with different pinhole arrays are analyzed to reveal the relationship between the aperture width of the pinhole array and the crosstalk. The optimal value of the aperture width of the pinhole array is also obtained to eliminate the crosstalk. A prototype using the optimal pinhole array is developed, and the experiment results agree well with the theory.
1. Introduction Integral imaging three-dimensional (3D) display presents 3D images with full color, full parallax and continuous viewpoints without special apparatus or coherent lights [1–6], and is simple in realizing a dual-view 3D display which presents different 3D images in different directions [7–10]. Thus, the integral imaging 3D display is regarded as a promising and feasible 3D display. However, the crosstalk still hinders its practical application. The crosstalk is caused when the lights emitted from each point light source partially illuminate its corresponding elemental image and partially illuminate the adjacent elemental images. Many methods have been proposed to eliminated the crosstalk. A double plano-convex microlens array is employed to reflect the crosstalk lights [11]. A tilted barrier array consisting of orthogonally polarized sheets is used to eliminated the crosstalk [12]. An integral imaging 3D display using a pyramid pinhole array is also proposed [13]. However, the double plano-convex microlens array, the tilted barrier array and the pyramid pinhole array are difficult to be fabricated. Therefore, we propose a crosstalk-free integral imaging 3D display using a pinhole array. 2. Theory and analysis The structure of the integral imaging 3D display using the pinhole array is shown in Fig. 1. It consists of a back light unit, a pinhole array and a liquid crystal panel. The pinhole array, which is attached to the back light unit, is located between the back light unit and the liquid crystal panel. According to different aperture widths of the pinhole arrays, three imaging models of the integral imaging 3D display are respectively established, as shown in Fig. 2. The parameters of three imaging models are identical except for the aperture widths of the pinhole arrays. The aperture widths of three pinhole arrays are gradually increased from the left to right. As shown in Fig. 2(a), each
⁎
Corresponding author. E-mail address: [email protected] (Q.-H. Wang).
https://doi.org/10.1016/j.ijleo.2019.03.153 Received 25 November 2018; Accepted 27 March 2019 0030-4026/ © 2019 Elsevier GmbH. All rights reserved.
Optik - International Journal for Light and Electron Optics 184 (2019) 538–541
F. Wu, et al.
Fig. 1. Structure of the integral imaging display using the pinhole array.
Fig. 2. Three schematic diagrams of the integral imaging display using the pinhole array.
Fig. 3. Parameters of the integral imaging display with the optimal pinholes.
elemental image on the liquid crystal panel is partially illuminated by the lights through the corresponding pinhole. Therefore, the reconstructed 3D images are incomplete, and the aperture width of the pinhole array in Fig. 2(a) is undersize. When the aperture width of the pinhole array is increased to a certain value, each elemental image is only illuminated by the lights through the 539
Optik - International Journal for Light and Electron Optics 184 (2019) 538–541
F. Wu, et al.
Table 1 Parameters of the prototype. Parameters
p (mm)
t (mm)
w (mm)
g (mm)
Values
2
0.4
0.2
1.8
Fig. 4. Element image array for the integral imaging display.
Fig. 5. 3D images reconstructed in the integral imaging display.
corresponding pinhole, as shown in Fig. 2(b). Another importance feature is that the light through each pinhole totally illuminates its corresponding elemental image. When the aperture width of the pinhole array is further increased, the light through each pinhole partially illuminates its corresponding elemental image and partially illuminates the adjacent elemental images, as shown in Fig. 2(c). In other words, the crosstalk is introduced by oversize aperture width of the pinhole array. As mentioned above, the aperture width of the pinhole array in Fig. 2(b) is optimal. Suppose that p is the pitch of the elemental image and the pinhole, g is the gap between the liquid crystal panel and the pinhole array, and t is the thickness of the pinhole array. According to the geometric relationships in Fig. 3, the optimal aperture width of the pinhole w is deduced as
w=
pt . 2g + t
(1)
The optimal aperture width of the pinhole is related to the pitch of the pinhole, the thickness of the pinhole array, and the gap between the liquid crystal panel and the pinhole array. It is important that the optimal aperture width of the pinhole is irrelevant to the viewing distance. The width of the viewing zone D is obtained as
D=
2lp + p. 2g + t
(2)
The viewing angle of the integral imaging 3D display θ is calculated as
p (m − 2) p ⎤ θ = 2 arctan ⎡ − . ⎥ ⎢ 2l ⎦ ⎣ 2g + t
(3)
3. Experimental results We developed a prototype of the integral imaging 3D display using the optimal pinhole array. The optimal pinhole array was printed by Screen Tanto 6120. The parameters of the prototype are shown in Table 1. The element image array used in the integral imaging 3D display is generated by a computer, as shown in Fig. 4. The 3D scene, which is composed of two letters “S” and “C” and consists of 48 × 27 elemental images. Each elemental image has 30 × 30 pixels. The viewing distance between the integral imaging 3D display and the observer is 200 mm. The 3D images reconstructed by the prototype are captured from different directions, as shown in Fig. 5. When the viewing angle is 14° to the left, two letters “S” and “C” are fully presented, as shown in Fig. 5(b). When the viewing angle is 14° to the right, two letters “S” and “C” are also fully reconstructed, and relative position of two letters “S” and “C” is changed, as shown in Fig. 5(c). The 540
Optik - International Journal for Light and Electron Optics 184 (2019) 538–541
F. Wu, et al.
flipping images aren’t seen beyond the viewing zone, as shown in Figs. 5(a) and (d). The experimental results prove that the crosstalk can be eliminated by optimizing the aperture width of the pinhole. 4. Conclusion A crosstalk-free integral imaging 3D display using the pinhole array is proposed. The relationship between the aperture width of the pinhole and the crosstalk is analyzed. The optimal value of the aperture width of the pinhole, which is irrelevant to the viewing distance, is deduced to eliminate the crosstalk. A prototype of the integral imaging 3D display is developed, and the experiment results agree well with the theory. The crosstalk-free integral imaging 3D display will have some applications. Acknowledgements The work is supported by the National Natural Science Foundation of China (NSFC) under Grant No. 61705022, the Chinese Postdoctoral Science Foundation under Grant No. 2019M592650, and the Applied Basic Research Programs of Science and Technology Department of Sichuan Province under Grant Nos. 2019JDRC0075 and 2019YJ0377. References [1] K.C. Kwon, M.U. Erdenebat, M.A. Alam, Y.T. Lim, K.G. Kim, N. Kim, Integral imaging microscopy with enhanced depth-of-field using a spatial multiplexing, Opt. Express 24 (2016) 2072–2083. [2] Y. Yuan, X.R. Wang, X.X. Wu, J.L. Zhang, Y. Zhang, Improved resolution integral imaging using random aperture coding based on compressive sensing, Optik 130 (2017) 413–421. [3] X.B. Yu, X.Z. Sang, X. Gao, Z.D. Chen, D. Chen, W. Duan, B.B. Yan, C.X. Yu, D.X. Xu, Large viewing angle three-dimensional display with smooth motion parallax and accurate depth cues, Opt. Express 23 (2015) 25950–25958. [4] Z. Wang, A.T. Wang, S.L. Wang, X.H. Ma, H. Ming, Resolution-enhanced integral imaging using two micro-lens arrays with different focal lengths for capturing and display, Opt. Express 23 (2015) 28970–28977. [5] Y.J. Wang, X. Shen, Y.H. Lin, B. Javidi, Extended depth-of-field 3D endoscopy with synthetic aperture integral imaging using an electrically tunable focal-length liquid-crystal lens, Opt. Lett. 40 (2015) 3564–3567. [6] Y. Yamaguchi, Y. Takaki, See-through integral imaging display with background occlusion capability, Appl. Opt. 55 (2016) 144–149. [7] Q.H. Wang, C.C. Ji, L. Li, H. Deng, Dual-view integral imaging 3D display by using orthogonal polarizer array and polarization switcher, Opt. Express 24 (2016) 9–16. [8] F. Wu, G.J. Lv, B.C. Zhao, H. Deng, Q.H. Wang, Dual-view integral imaging three-dimensional display using polarized glasses, Appl. Opt. 57 (2018) 4019–4021. [9] J. Jeong, C.K. Lee, K. Hong, J. Yeom, B. Lee, Projection-type dual-view three-dimensional display system based on integral imaging, Appl. Opt. 53 (2014) 12–18. [10] F. Wu, H. Deng, C.G. Luo, D.H. Li, Q.H. Wang, Dual-view integral imaging three-dimensional display, Appl. Opt. 52 (2013) 4911–4914. [11] Y. Wang, Q. Wang, D. Li, H. Deng, C. Luo, Crosstalk-free integral imaging based on double plano-convex micro-lens array, Chin. Opt. Lett. 11 (2013) 061101. [12] S. Tang, Y.Z. Wang, H. Deng, C.C. Ji, Q.H. Wang, Doubleviewing-zone integral imaging 3D display without crosstalk based on a tilted barrier array, J. Soc, Inf. Disp. (1975) 21 (2013) 198–202. [13] H. Deng, Q.H. Wang, F. Wu, C.G. Luo, Y. Liu, Cross-talk-free integral imaging three-dimensional display based on a pyramid pinhole array, Photon. Res. 3 (2015) 173–176.
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Contents lists available at ScienceDirect
Optik journal homepage: www.elsevier.com/locate/ijleo
Original research article
Crosstalk-free integral imaging 3D display using pinhole array Fei Wua,c, Guo-Jiao Lva, Bai-Chuan Zhaoa, Ze-Sheng Liua, Qiong-Hua Wangb,
⁎
T
a
School of Electronics Engineering, Chengdu Technological University, Chengdu, 611730, China School of Instrumentation Science and Opto-electronics Engineering, Beihang University, Beijing, 100191, China c School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, 610054, China b
A R T IC LE I N F O
ABS TRA CT
Keywords: Integral imaging Pinhole array Crosstalk Aperture width
We propose a crosstalk-free integral imaging three-dimensional (3D) display using a pinhole array. It consists of a back light unit, a pinhole array and a liquid crystal panel. The pinhole array, which is attached to the back light unit, is located between the back light unit and the liquid crystal panel. Three imaging models of the integral imaging 3D display with different pinhole arrays are analyzed to reveal the relationship between the aperture width of the pinhole array and the crosstalk. The optimal value of the aperture width of the pinhole array is also obtained to eliminate the crosstalk. A prototype using the optimal pinhole array is developed, and the experiment results agree well with the theory.
1. Introduction Integral imaging three-dimensional (3D) display presents 3D images with full color, full parallax and continuous viewpoints without special apparatus or coherent lights [1–6], and is simple in realizing a dual-view 3D display which presents different 3D images in different directions [7–10]. Thus, the integral imaging 3D display is regarded as a promising and feasible 3D display. However, the crosstalk still hinders its practical application. The crosstalk is caused when the lights emitted from each point light source partially illuminate its corresponding elemental image and partially illuminate the adjacent elemental images. Many methods have been proposed to eliminated the crosstalk. A double plano-convex microlens array is employed to reflect the crosstalk lights [11]. A tilted barrier array consisting of orthogonally polarized sheets is used to eliminated the crosstalk [12]. An integral imaging 3D display using a pyramid pinhole array is also proposed [13]. However, the double plano-convex microlens array, the tilted barrier array and the pyramid pinhole array are difficult to be fabricated. Therefore, we propose a crosstalk-free integral imaging 3D display using a pinhole array. 2. Theory and analysis The structure of the integral imaging 3D display using the pinhole array is shown in Fig. 1. It consists of a back light unit, a pinhole array and a liquid crystal panel. The pinhole array, which is attached to the back light unit, is located between the back light unit and the liquid crystal panel. According to different aperture widths of the pinhole arrays, three imaging models of the integral imaging 3D display are respectively established, as shown in Fig. 2. The parameters of three imaging models are identical except for the aperture widths of the pinhole arrays. The aperture widths of three pinhole arrays are gradually increased from the left to right. As shown in Fig. 2(a), each
⁎
Corresponding author. E-mail address: [email protected] (Q.-H. Wang).
https://doi.org/10.1016/j.ijleo.2019.03.153 Received 25 November 2018; Accepted 27 March 2019 0030-4026/ © 2019 Elsevier GmbH. All rights reserved.
Optik - International Journal for Light and Electron Optics 184 (2019) 538–541
F. Wu, et al.
Fig. 1. Structure of the integral imaging display using the pinhole array.
Fig. 2. Three schematic diagrams of the integral imaging display using the pinhole array.
Fig. 3. Parameters of the integral imaging display with the optimal pinholes.
elemental image on the liquid crystal panel is partially illuminated by the lights through the corresponding pinhole. Therefore, the reconstructed 3D images are incomplete, and the aperture width of the pinhole array in Fig. 2(a) is undersize. When the aperture width of the pinhole array is increased to a certain value, each elemental image is only illuminated by the lights through the 539
Optik - International Journal for Light and Electron Optics 184 (2019) 538–541
F. Wu, et al.
Table 1 Parameters of the prototype. Parameters
p (mm)
t (mm)
w (mm)
g (mm)
Values
2
0.4
0.2
1.8
Fig. 4. Element image array for the integral imaging display.
Fig. 5. 3D images reconstructed in the integral imaging display.
corresponding pinhole, as shown in Fig. 2(b). Another importance feature is that the light through each pinhole totally illuminates its corresponding elemental image. When the aperture width of the pinhole array is further increased, the light through each pinhole partially illuminates its corresponding elemental image and partially illuminates the adjacent elemental images, as shown in Fig. 2(c). In other words, the crosstalk is introduced by oversize aperture width of the pinhole array. As mentioned above, the aperture width of the pinhole array in Fig. 2(b) is optimal. Suppose that p is the pitch of the elemental image and the pinhole, g is the gap between the liquid crystal panel and the pinhole array, and t is the thickness of the pinhole array. According to the geometric relationships in Fig. 3, the optimal aperture width of the pinhole w is deduced as
w=
pt . 2g + t
(1)
The optimal aperture width of the pinhole is related to the pitch of the pinhole, the thickness of the pinhole array, and the gap between the liquid crystal panel and the pinhole array. It is important that the optimal aperture width of the pinhole is irrelevant to the viewing distance. The width of the viewing zone D is obtained as
D=
2lp + p. 2g + t
(2)
The viewing angle of the integral imaging 3D display θ is calculated as
p (m − 2) p ⎤ θ = 2 arctan ⎡ − . ⎥ ⎢ 2l ⎦ ⎣ 2g + t
(3)
3. Experimental results We developed a prototype of the integral imaging 3D display using the optimal pinhole array. The optimal pinhole array was printed by Screen Tanto 6120. The parameters of the prototype are shown in Table 1. The element image array used in the integral imaging 3D display is generated by a computer, as shown in Fig. 4. The 3D scene, which is composed of two letters “S” and “C” and consists of 48 × 27 elemental images. Each elemental image has 30 × 30 pixels. The viewing distance between the integral imaging 3D display and the observer is 200 mm. The 3D images reconstructed by the prototype are captured from different directions, as shown in Fig. 5. When the viewing angle is 14° to the left, two letters “S” and “C” are fully presented, as shown in Fig. 5(b). When the viewing angle is 14° to the right, two letters “S” and “C” are also fully reconstructed, and relative position of two letters “S” and “C” is changed, as shown in Fig. 5(c). The 540
Optik - International Journal for Light and Electron Optics 184 (2019) 538–541
F. Wu, et al.
flipping images aren’t seen beyond the viewing zone, as shown in Figs. 5(a) and (d). The experimental results prove that the crosstalk can be eliminated by optimizing the aperture width of the pinhole. 4. Conclusion A crosstalk-free integral imaging 3D display using the pinhole array is proposed. The relationship between the aperture width of the pinhole and the crosstalk is analyzed. The optimal value of the aperture width of the pinhole, which is irrelevant to the viewing distance, is deduced to eliminate the crosstalk. A prototype of the integral imaging 3D display is developed, and the experiment results agree well with the theory. The crosstalk-free integral imaging 3D display will have some applications. Acknowledgements The work is supported by the National Natural Science Foundation of China (NSFC) under Grant No. 61705022, the Chinese Postdoctoral Science Foundation under Grant No. 2019M592650, and the Applied Basic Research Programs of Science and Technology Department of Sichuan Province under Grant Nos. 2019JDRC0075 and 2019YJ0377. References [1] K.C. Kwon, M.U. Erdenebat, M.A. Alam, Y.T. Lim, K.G. Kim, N. Kim, Integral imaging microscopy with enhanced depth-of-field using a spatial multiplexing, Opt. Express 24 (2016) 2072–2083. [2] Y. Yuan, X.R. Wang, X.X. Wu, J.L. Zhang, Y. Zhang, Improved resolution integral imaging using random aperture coding based on compressive sensing, Optik 130 (2017) 413–421. [3] X.B. Yu, X.Z. Sang, X. Gao, Z.D. Chen, D. Chen, W. Duan, B.B. Yan, C.X. Yu, D.X. Xu, Large viewing angle three-dimensional display with smooth motion parallax and accurate depth cues, Opt. Express 23 (2015) 25950–25958. [4] Z. Wang, A.T. Wang, S.L. Wang, X.H. Ma, H. Ming, Resolution-enhanced integral imaging using two micro-lens arrays with different focal lengths for capturing and display, Opt. Express 23 (2015) 28970–28977. [5] Y.J. Wang, X. Shen, Y.H. Lin, B. Javidi, Extended depth-of-field 3D endoscopy with synthetic aperture integral imaging using an electrically tunable focal-length liquid-crystal lens, Opt. Lett. 40 (2015) 3564–3567. [6] Y. Yamaguchi, Y. Takaki, See-through integral imaging display with background occlusion capability, Appl. Opt. 55 (2016) 144–149. [7] Q.H. Wang, C.C. Ji, L. Li, H. Deng, Dual-view integral imaging 3D display by using orthogonal polarizer array and polarization switcher, Opt. Express 24 (2016) 9–16. [8] F. Wu, G.J. Lv, B.C. Zhao, H. Deng, Q.H. Wang, Dual-view integral imaging three-dimensional display using polarized glasses, Appl. Opt. 57 (2018) 4019–4021. [9] J. Jeong, C.K. Lee, K. Hong, J. Yeom, B. Lee, Projection-type dual-view three-dimensional display system based on integral imaging, Appl. Opt. 53 (2014) 12–18. [10] F. Wu, H. Deng, C.G. Luo, D.H. Li, Q.H. Wang, Dual-view integral imaging three-dimensional display, Appl. Opt. 52 (2013) 4911–4914. [11] Y. Wang, Q. Wang, D. Li, H. Deng, C. Luo, Crosstalk-free integral imaging based on double plano-convex micro-lens array, Chin. Opt. Lett. 11 (2013) 061101. [12] S. Tang, Y.Z. Wang, H. Deng, C.C. Ji, Q.H. Wang, Doubleviewing-zone integral imaging 3D display without crosstalk based on a tilted barrier array, J. Soc, Inf. Disp. (1975) 21 (2013) 198–202. [13] H. Deng, Q.H. Wang, F. Wu, C.G. Luo, Y. Liu, Cross-talk-free integral imaging three-dimensional display based on a pyramid pinhole array, Photon. Res. 3 (2015) 173–176.
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