Presentation No. LDC-5-02 (21 Apr. 2021)
The 10th Laser Display and Lighting Conference 2021 (LDC 2021), Apr. 19 - Apr. 22, 2021
© OPTICS & PHOTONICS International 2021

Large-Scale Full-Parallax Full-Color Computer-Generated Holograms
Reconstructed by Laser/LED Lighting
Kyoji Matsushima 1

1 Department of Electrical and Electronic Engineering, Kansai University,

Yamate-cho 3-3-35, Suita, Osaka 564-8680, Japan, +81-6-6368-0933, matsu@kansai-u.ac.jp
Abstract: Two techniques are introduced to create full-color computer-generated holograms that have very large-scale such as tensof billion pixels and reconstruct a very impressive deep 3D scene. In the techniques, white LEDs and RGB laser are used as theillumination light source. Optical reconstruction of these full-color CGHs are demonstrated in this paper.

1. Introduction
Computer holography, the technique to createholographic 3D images using a computer, has beendeveloped over the last decade [1]. The createdholograms, called computer-generated holograms (CGH),
can reconstruct 3D images of non-physical objects
unlike traditional optical holography. Unfortunately,
creating high-quality CGHs had been impossible for along time because of the gigantic space-band productrequired for realizing a given large viewing angle andscreen size. We developed several techniques that makeit possible to calculate and fabricate large-scale CGHs,
called high-definition CGHs, which are composed ofbillions or sometimes tens or hundreds of billion pixels(Chap. 1 in [1]). The large-scale CGHs reconstructspatial 3D images of a deep scene with natural motion
parallax in full-parallax. The 3D images, in fact, arebeing comparable to those in traditional opticalholography. As a result, the CGHs give great impact ofstrong sensation of depth to viewers.
However, it was very difficult to reconstruct fullcolor images by these high-definition CGHs because theprinted CGHs are a type of thin hologram. The 3D
images reconstructed under a white-light illumination
cause many smears because of chromatic aberration.
Recently, two methods: CGHs with RGB color filters [2,3] and stacked CGVHs (computer-generated volumehologram) [4] were invented for reconstructing full color
images from high-definition CGHs. These full-colorCGHs are reconstructed using a white LED or RGB laser
light sources.
Full-color 3D image

Printed fringeColor filter

White lightFig. 1. Full-color reconstruction of high-definition
CGHs using RGB color filters.

5.2 cmMulti-chip
white LED

Fig. 2. Full-color reconstruction of a high-definition
CGH using RGB color filters [2]. Video link,
https://doi.org/10.1364/OE.25.002016.v001

2. CGH with RGB color filters
In this technique, RGB color filters that are very similar
to those used in LCD panels are attached to the largescale fringe pattern, and the fringe pattern behind thefilters is generated at appropriate wavelengths
corresponding to the RGB colors, as shown in Fig. 1.
2.1 Illumination light sources
CGHs with RGB color filters can be reconstructed byboth LEDs and RGB lasers. When using an LED,
because the bandwidth of the RGB color filters iscommonly not so narrow, a multi-chip type white LEDshould be used instead of a single-chip type withphosphor to reconstruct sharp 3D images. The problemof the bandwidth is properly avoided by use of an RGB
laser source.
2.2 Optical reconstruction
Optical reconstruction using a multi-chip white LED isshown in Fig. 2. The 3D image is blurred a little by thewideband property of the illumination. Coherent
illumination using an RGB laser makes the reconstructed
image much sharper as shown in Fig. 3. Here, an ultrashort focus projector made by SONY™, where RGB laser
diodes (LD) are installed, is used for the light source, asin (d). Note that the projector throws just a plane white
image in this case. We can also use discrete RGB-LD
components for the illumination, as in (e).

The 10th Laser Display and Lighting Conference 2021 (LDC 2021), Apr. 19 - Apr. 22, 2021
© OPTICS & PHOTONICS International 2021

Ultra shortfocus projector

Optical fiberDiffuser(b)(c)(a)(d)(e)Fig. 3. A CGH with RGB color filters reconstructed using RGB lasers. A close-up image (a), and images from (b) left and(c) right viewpoints (Sect. 15.6.4 in [1]); Illumination using (d) a laser projector and (e) RGB laser.
Video link, https://youtu.be/DmC93CRdhFQ

3. Stacked CGVH
Another way to reconstruct full-color 3D images from ahigh-definition CGH is stacking computer-generated
volume holograms (CGVH) [4]. A volume hologram,
sometimes called a “thick” hologram, is a different typeof hologram. The volume hologram cannot be created byprinting the fringe pattern because the fringe has a 3D
structure in the recording material such as photopolymer.
We can fabricate CGVHs by transferring the originalCGH, printed using laser lithography (Sect. 15.3 in [1]),to photopolymer using the technique of contact-copy.
A volume hologram has strong wavelengthselectivity based on Bragg reflection, and can bereconstructed by reflection illumination only atwavelength used in the contact copy. Thus, we canreconstruct full-color images by fabricating three
CGVHs from three original printed CGHs and stacking
the CGVHs, as shown in Fig. 4. The hologram
reconstructs very fine 3D images shown in Fig. 5 using asingle-chip white LED, which has a broadband property,
because of the excellent wavelength selectivity of theCGVHs.
OriginalCGHRContactcopy(R laser)

OriginalCGHGContactcopy(G laser)

Volumehologram

RG

Acknowledgment
This work was partially supported by Japan Society for
the Promotion of Science (JSPS) KAKENHI 18H03349.
References[1] K. Matsushima, Introduction to Computer Holography(Springer, 2020).
[2] Y. Tsuchiyama and K. Matsushima, “Full-color largescaled computer-generated holograms using RGB colorfilters,” Opt. Express 25, 2016–2030 (2017).
[3] K. Matsushima and N. Sonobe, “Full-color digitized
holography for large-scale holographic 3D imaging ofphysical and nonphysical objects,” Appl. Opt. 57, A150–
A156 (2018).
[4] O. Kunieda and K. Matsushima, “High-quality full-parallax
full-color three-dimensional image reconstructed bystacking
large-scalecomputer-generated
volumeholograms,” App. Opt. 58, G104-G111(2019).

OriginalCGH

B

Contactcopy(B laser)

Volumehologram

4. Conclusion
Full-color reconstruction of large-scale CGHs isachieved by two methods using a white LED and RGB
laser light source.

5.2 cmVolumehologram

BPigtail white LED
White light

Fig. 4. The principle of stacked CGVHs.

Fig. 5. Full-color reconstruction of the stacked CGVH
using a broadband pigtail white LED [4]. Video link,
https://doi.org/10.6084/m9.figshare.8870177.v1