Proceedings of 2nd International Symposium for Color Science and Art 2020

Development of multicolor-holographic flip-books systems
using lithium-niobate crystals
Jun Chen, Mitsunori Toyoda, Yukihiro Ishii*,**Tokyo Polytechnic Univ., 1583 Iiyama, Atsugi, Kanagawa 243-0297, Japan* Tokyo Univ. of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, JAPAN** RIKEN Center for Advanced Photonics, Wako 351-0198, Japan
LN crystal as holograms while the LN crystal is rotated byan angle of 0.2°. After that, we can observe a color
animation by rotating the LN crystal with respect to a laser
beam, otherwise by using a LED broad-spectral source [7].

ABSTRACT
A multicolor holographic flip-books system ispresented, in which angle-multiplexed image plane
holograms are recorded using an Fe-doped LiNbO3(LN) crystal as recording media with a 532-nm green
laser. A 633-nm red He-Ne laser, the 532-nm green
laser, and a 432-nm blue diode laser were used toilluminate the recorded holograms. Multicolor flip-books
are obtained when the LN crystal was slowly rotated.
Bragg mismatching from the use of three wavelengths
is compensated by changing the reconstructing angles.
1. INTRODUCTION
We describe a multicolor-holographic flip-books systemusing Fe-doped LiNbO3 (LN) crystals. By using the system,
color animation can be observed by rotating the crystal
about the half angle of the recording beam.
Being different from the conventional hologram recorded
on a thin recording material, volume hologram using athick material allows the angle-multiplexed hologram
recording [1]. Thus, volume hologram has proved to bevery useful for optical memory due to the large storage
capacity and fast transfer rate. Moreover, photorefractive
materials like LN crystal can be used as a rewritable
recording media, the images can be erased and rewritten
again. Thanks to the angle-multiplexing property, it’sinteresting to use the LN crystal as a holographic recording
material for recording multicolor flip-books.
Fourier-transform scheme has been used to record thehologram in LN crystals. However, Bragg-mismatchoccurs when we use a light source with a different
wavelength for hologram reconstruction. We will be able toget only a part of image rather than a whole original image
since volume hologram acts as a band pass filter getting
through the bandlimited spatial frequencies of an input
image. Several techniques have been proposed to relievethat problems: using a spherical [2] or polychromatic [3]reconstructing wave to match the Bragg condition. On theother hand, an image hologram [3] can produces a wholeimage. We demonstrate the whole-image reconstructions
from an image-plane volume hologram with a Fe-doped
LN crystal. A LN volume hologram can record a number ofmultiplexed images with the rotation of a crystal [4].

Fig. 1 Concept of the flip-books
3. THEORY AND OPTICAL SYSTEM
Fig. 2 shows a schematic configuration of the opticalsystem used for recording and reconstructing the flipbooks system.

Fig. 2 Optical setup
A diode-pumped solid-state (DPSS) laser (CoherentCompass 315M-100SL, 532nm, 100mW) is used forrecording the holograms. The light beam from the DPSS
laser is split using a Beam-split into two beams. One isused to illuminate a liquid-crystal device (LCD) on which
the input images were displayed, and the light wave
passing through the LCD was imaged with a 4-f opticalsystem onto the LN crystal as the object wave. The otherbeam is expanded and then used as a reference wave.
The object and reference waves with a cross angle of 30°
overlapped on the LN crystal and form an interference

2. CONCEPTThe concept of the proposed multicolor-holographic flipbooks system [5,6] is schematically shown in Fig.1. The
images forming the flip-books are multiply recorded on an27

Proceedings of 2nd International Symposium for Color Science and Art 2020
4.3 Demonstration of color flip-books
As a demonstration, multi-color flip-books was made.
During the experiments, the original images was send toLCD one by one, and recorded with the reference beam,
while the LN crystal was rotated by 0.2 degree between
two adjacent images.

fringe patterns. In the bright region of the fringe patterns,
the electrons of Fe level were excited, moved to dark
region and finally formed a space-charge field that
produces a space refractive index distribution via Pockels
effect. In this way the input image was recorded on the LN
crystal as a transparent image hologram. Because of thesharp Bragg condition, the next image can be recorded byslightly rotating the crystal.
In multi-color observation of the flip-books, a He-Ne laser(632.8nm, 10mW), a DPSS laser described above, and adiode-laser (432nm, 8mW) were used as light sources.
The incident angle R for a red laser beam and B for a bluelaser beam are set as R sin1  R / G  sin G  andB sin1 B / G  sin G to match the Bragg condition

due to the wavelength difference between the recordingand readout lasers.
4. EXPERIMENTAL RESULTS
4.1 Exposure time reduction
In our experiments, a Fe-doped LN crystal of 10-mm
square and 4-mm thickness was used. Usually, a relatively
long time up to several minutes was required to record thehologram into LN crystal. We developed the recording
efficiency for different polarization condition for the firsttime. The p-polarization is quite better than s-polarization
usually used. The intensity dependence on the exposure
time is shown in Fig. 3. The exposure time can be reduced
from hundreds to seconds.

Intensity (a.u.)

10P-in, P-out

8S-in, P-out

Fig. 5 Demonstration of a RGB color flip-books
5. CONCLUSION
A multicolor holographic flip-boos system is presented.
The original images were recorded on a rewritable
photorefractive media, Fe-doped LN crystal, we canobserve a color animation by slowly rotating the crystal
with RGB illumination laser lights. By optimize the incident
light polarization condition, the exposure-time reduction
from hundreds to seconds enabled us to easily record alarge amount of images into the crystal.

S-in, S-out

6420

12 Exposure
3 time（min）
45

6. Acknowledgment
This work was supported by “FY2016 MEXT Private
University Research Branding Project”

6

7. REFERENCES[1] K. Buse, A. Adibi and D. Psaltis, Nature, pp. 665- 668,
Vol. 393(1998).
[2] R. Fujimura, T. Shimura, and K. Kuroda: Optics
Express, pp. 1091-109818, Vol. 18 (2010).
[3] Y. Komori and Y. Ishii: Proc. of SPIE, pp. 1-7,Vol.778119 (2010).
[4] T. Sato, J. Chen, and Y. Ishii, , Proc. of The Eleventh
Finland-Japan Joint Symposium on Optics inEngineering, pp1-2 (2015).
[5] T. Hosono, S. Hikota, J. Chen, M. Toyoda, Y. Ishii, The
80th JSAP Autumn Meeting, 20a-PA1-1(2019).
[6] F. Shishido, Y. Okeya, J. Chen, M. Toyoda, Y. Ishii,Optics & Photonics Japan 2019, 3pP12 (2019).
[7] S. Nakadate, Y. Tokuyama, Y. Kume, M. Shibuya, J.
Chen, Y. Azuma, T. Moriyama, Optical Review, PP.478486, Vol.26, No.5, PP.478-486 (2019).

Fig. 3 Reconstruction image intensity at different
polarization condition
4.2 Angle separation
Another important issue in forming flip-books is angle
separation. We found there is no cross talk with a minimum
angle separation of 0.2°as shown in Fig. 4.

Fig. 4 Reconstructed images with an angleseparation of 0.2°

28