International Symposium on Holography and Related Technologies 2015 (IWH2015)
Ginowan (Okinawa), We5-P8, (2015.12.2).

Capture of Large-Scaled Wave Fields
for Full-Color Digitized Holography
Noriaki Sonobe, Yasuhiro Tsuchiyama, and Kyoji Matsushima
Department of Electrical and Electronic Engineering, Kansai University
3-3-35, Yamate-cho, Suita, Osaka 564-8680, Japan

1. Introduction
In the past few years, computer holography successfully created high-definition computer-generated
holograms (CGH) such as “Brothers” and “The Venus” [1]. In these CGHs, the 3D images ofpolygon-meshed CG models, i.e. virtual objects are optically reconstructed with the strong sensation of depth.
However, high-definition CGHs reconstruct not only virtual objects but also real-existing physical object. In
this case, the wave field emitted from physical objects is recorded by employing synthetic aperture digitalholography (DH) and optically reconstructed by high-definition CGHs [2]. We call this technique digitized
holography, because the whole process of traditional holography is digitized in this technique.
Recently, full-color reconstruction of high-definition CGHs for virtual objects is also realized by using
dichroic mirrors [3] and color filters [4]. Thus, it is properly expected that physical objects can bereconstructed in full-color. However, three object fields of a physical object must be recorded with three
wavelengths corresponding to RGB primary colors to reconstruct its full-color 3D images. In this paper, thetechnique of synthetic aperture DH with RGB three wavelengths is reported for realizing full-color digitized
holography. Full-color simulated reconstruction of the generated CGH is also presented to verify thetechnique.
2. Recording object fields by synthetic aperture DH
Figure 1 shows the experimental setup for synthetic aperture DH with three wavelengths corresponding toRGB primary colors. The parameters used in the experiment are summarized in Table 1. The image sensor
mounted on stages scans the area of the object field and records the fringe generated by optical interference.
The phase shifting technique is used for removing the conjugate image and 0-th order light. Lensless Fourier
setup using a spherical reference field makes it possible to convert the sampling density. In this experiment,
we actually recorded the object fields over the area of approximately 11.4 × 11.4 cm2 at interval of less than
1 μm. Here note that three fringes are recorded for phase shifting prior to changing the wavelength, because
the amount of phase shift depends on the wavelength. After recording three fields at a given position, theimage sensor stages moves 10 mm in horizontal or 7.2 mm in vertical direction.
He-Ne laser
Figure 2 shows captured fields and Fourierλ = 632.8nm NDF1 BS2 BS3 BS4transformed object fields. Since samplingM2
interval depends on the wavelength, weSF1
Shutter 1 1/2RP1
ImageSenser ys
resampled the field using bicubic interpolation to1/2RP4BS5
adjust the interval of all captured fields to 1μm.
ObjectDPSS laser
λ = 488nm

NDF2

BS1xs

Table 1 Parameters used for capturing object fields.
Wavelengths [nm]488，532，633

Number of samplings used fornumerical calculation

32,768 × 32,768

Sensor pitches [μm]3.5 × 3.5

Number of segments
Distance between reference point
source and sensor [mm]12 × 16250

Shutter 2 1/2RP2DPSS laser
λ = 532nm NDF3

Shutter 3

1/2RP3

SF3SF2
M1M5M3StageM4

M6 with Piezo phase shifterFig.1 Experimental setup for capturing large-scaled
wave-fields by using lensless-Fourier syntheticaperture DH.

International Symposium on Holography and Related Technologies 2015 (IWH2015)
Ginowan (Okinawa), We5-P8, (2015.12.2).

3. Simulated reconstruction of full-color CGHs
A fringe pattern was generated for creating the high-definition CGH and reconstructing the captured field.
The 3D scene and parameters are shown in Fig.3 and Table 2, respectively. Figure 4 shows full-color
simulated reconstructions from different viewpoints, which are calculated by the numerical image formation
technique. Here, we assumed the optical system using dichroic mirrors for full-color reconstruction [3].
It is verified that the object fields are properly
recorded by the proposed technique, but a little color
changes are observed when the viewpoint continuouslymoves. Vertically-striped noises also occurs in thereconstructed images.
4. Conclusion
We proposed the technique for capturing large-scaled
object fields using synthetic aperture DH with RGB
three wavelengths. The full-color 3D image issuccessfully reconstructed by the CGH generated fromthe captured fields in simulation, though several
degradations are found in the reconstructed images.
This work was supported by the JSPS KAKENHI(15K00512) and the MEXT strategic research foundation
at private universities (2013-2017)

λ=488nm
λ=532nm
λ=633nm(a) Captured wave fields (amplitude image)

λ=488nm
λ=633nm
λ=532nm(b) Fourier-transformed images (amplitude image)Fig.2 Captured object fields with three wavelengths

Reference1) K. Matsushima, S. Nakahara: “Extremely high-definition Table 2 Parameters used for creating the CGH.
full-parallax computer-generated hologram created by the Number of samplings
32,768 × 32,768
polygon-based method”, Appl. Opt. 48, H54-H63 (2009).
Pixels pitches [μm]1.0 × 1.02) K. Matsushima, Y. Arima, S. Nakahara: “Digitized Design wavelength [nm]488, 532, 633
holography: modern holography for 3D imaging of virtual
Unit : mmand real objects”, Appl. Opt. 50, H278-H284 (2011).
yObject3) T. Miyaoka, K. Matsushima, S. Nakahara: “Optimization ofHologram32
design-wavelength for unobtrusive chromatic aberration inx
high-definition color computer holography”, SPIE Proc.
9386, 93860N (2015).
25z4) Y. Tsuchiyama, K. Matsushima, S. Nakahara, Y. Sakamoto:
32.7“A simulation technique for selection of color filter used for
32.7
full-color high-definition CGH”, IWH2015 (to be100published).
Fig.3 3D scene of the CGH.

LeftCanter

Right

Fig.4 Full-color simulated reconstruction of the captured fields using dichroic mirrors.