5th EOS Topical Meeting on Optical Microsystems, Capri (Italy), (2013.9.13, Invited).

Computer holography: a perfect digital 3D techniquefor real and virtual objects

Kyoji Matsushima1, Sumio Nakahara2
Kansai University, Department of Electrical and Electronic Engineering
2
Kansai University, Department of Mechanical Engineering
Yamate-cho 3-3-35, Suita, Osaka 564-8680, Japanemail: matsu@kansai-u.ac.jp

1

Summary
Recent developments in computer holography are reviewed. In computer holography,
the holographic fringe pattern is generated as a digital 2D image in extremely
high-definition and printed by using a laser lithography system. The 3D scenes
include CG model objects as well as physical objects captured by digital holography.
Introduction
Techniques in high-definition computer holography are rapidly developed in past
several years [1-4]. The high-definition computer-generated holograms (CGH)
created by the techniques are composed of more than billions pixels and reconstructfine 3D images comparable to that in conventional optical holography. Whereas
optical holography records/reconstructs only real-existing physical objects and unable
to store and transmit the images in digital media, computer holography reconstructs
virtual objects as well as real objects without any limitation on use of digital media.
Objects reconstructed in computer holography are mainly classified in twocategories. One is the CG-modeled virtual objects given by numerical data such as
polygon meshes. In this case, the object wave is obtained from much time-consuming
numerical calculation. The polygon-based method [5] and silhouette method [6]successfully resolve the problem and allow us to create occluded virtual 3D scenes.
Figure 1 shows the 3D scene of the optical reconstruction of a high-definition CGH,
named “Brothers” and exhibited at MIT museum in Boston, USA [7].
The other is real-existing physical objects like optical holography. In this case, theobject wave is digitally recorded by the technique of digital holography using image
sensors. This technique is sometimes called Digitized Holography, because ofreplacing the whole process in optical holography by digital counterparts. These twotypes of objects are freely arranged in a given 3D scene by field-based digital editing.
Techniques in computer holography
The polygon-based method is used for computing the wave-field (object wave) ofan object given by polygon-mesh data and definitely reduces computation time asBackground
Face1

Hologram

Face2

10.5(a)28
Units: cm2015

12.6(b)Fig.1 An example of the high-definition CGH [7]. (a) 3D scene, (b) optical reconstruction.

5th EOS Topical Meeting on Optical Microsystems, Capri (Italy), (2013.9.13, Invited).
Local
Cubic object coordinates
y2
y2
3y^
Globalcoordinates

21z2x2^yx2
Amplitudex^

Phase

Amplitudex^(a)(b)(c)z^Fig.2 The principle of the polygon-based method [4]. (a) object model, (b) surface function
for polygon #2, (c) amplitude image of wave-field calculated for polygon #2.

compared with point-based methods commonly used [5]. Figure 2 shows the principle
for calculating the wave-fields of surface sources of light.
In digitized holography, the wave-fields of physical objects are captured by digitalholography. However, current image sensors cannot satisfy requirements forhigh-definition computer holography, which are more than 109 of the number of pixels
and less than 1 m of the pixel pitch. Therefore, the technique of lensless-Fourier
synthetic aperture is used for capturing. In contrast with traditional optical holography,
we can easily edit the captured image and scene in digitized holography. For example,
the object images can be duplicated and resized [8], as shown in Fig.3.
The wave-fields of objects, calculated or captured, are mixed according to thedesign of the 3D scene. The silhouette method is used for shielding light behindobjects and preventing the reconstructed objects from being see-through image [2,6].
Conclusion
Computer holography makes it possible to create perfect 3D images without any
confliction of depth cues unlike conventional 3D systems.
This work was supported by research grants from the JSPS (KAKENHI, 24500133)
and the MEXT strategic research foundation at private universities (2013-2017).
References
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]

K. Matsushima, S. Nakahara, Appl. Opt., 48, H54 (2009).
K. Matsushima, Y. Arima, S. Nakahara, Appl. Opt., 50, H278 (2011).
H. Nishi, K. Matsushima, S. Nakahara, Appl. Opt., 50, H245 (2011).
K. Matsushima, H. Nishi, S. Nakahara, J. Electron. Imaging, 21, 023002 (2012).
K. Matsushima, Appl. Opt., 44, 4607 (2005).
K. Matsushima, A. Kondoh, SPIE Proc. 5290, 90 (2004).
K. Matsushima, S. Nakahara, SPIE Newsroom, Nov. 6, (2012).
D. Fujita, K. Matsushima, S. Nakahara, OSA Topical Meeting on Digital Holography andThree-Dimensional Imaging 2013, Hawaii, DW2A.7(2013).
65

Backgroun Fields of resized objects
d65

65

65

M=1.5
M=0.530
120
Units:mOriginal object(a) m100

50

50

M=0.25Hologramz(b)fieldFig. 3. An example of digitized holography [8]. (a) 3D scene, (b) optical reconstruction.