TeraFoils: Design and Rapid Fabrication Techniques for Binary
Holographic Structures in the Terahertz Region
Kenta Yamamoto
University of Tsukuba
Tsukuba, Japankenta.yam@digitalnature.slis.tsukuba.ac.jp

Kosaku Namikawa

Yoichi Ochiai

University of Tsukuba
Tsukuba, Japan

University of Tsukuba,
R&D Center for Digital Nature
Pixie Dust Technologies, Inc.
Tsukuba, Japanwizard@slis.tsukuba.ac.jp

Hologram of Silver Foils in Cards

SourceSensorHologram

Simulation

Terahertz View

Result (96x96 px)

Figure 1: Left: holographic tag card of TeraFoils. Center: experimental setup with sub-terahertz detector array and subterahertz source. Right: hologram generated by the proposed method, simulated result, and captured result (SIGGRAPH logo).

ABSTRACTIn this paper, we introduce TeraFoils, a method for designing andfabricating material-based structures using binary holograms in theterahertz region. We outline the design, fabrication, imaging, anddata processing steps for embedding information inside physicalobjects and exploring a method to create holographic structureswith silver-foiled paper. This paper is a sheet on which silver foil ispasted where the ink is printed, using a home-use laser printer andan electric iron. Wave propagation calculations were performed
to design a binary-amplitude hologram. Along with the designed
pattern, we fabricated silver-foiled binary holograms in the subterahertz range (0.1 THz) and confirmed their functions using a
two-dimensional THz sensor.

CCS CONCEPTS• Human-centered computing → User interface toolkits.

KEYWORDS
digital fabrication, terahertz, hologram, data encoding, material

SIGGRAPH ’21 Posters, August 09-13, 2021, Virtual Event, USA© 2021 Copyright held by the owner/author(s).
This is the author’s version of the work. It is posted here for your personal use. Notfor redistribution. The definitive Version of Record was published in Special Interest
Group on Computer Graphics and Interactive Techniques Conference Posters (SIGGRAPH’21 Posters), August 09-13, 2021, https://doi.org/10.1145/3450618.3469157.

ACM Reference Format:
Kenta Yamamoto, Kosaku Namikawa, and Yoichi Ochiai. 2021. TeraFoils:
Design and Rapid Fabrication Techniques for Binary Holographic Structuresin the Terahertz Region. In Special Interest Group on Computer Graphics andInteractive Techniques Conference Posters (SIGGRAPH ’21 Posters), August
09-13, 2021. ACM, New York, NY, USA, 2 pages. https://doi.org/10.1145/3450618.3469157

1INTRODUCTION

The development of light sources in the electromagnetic frequency
band of approximately 0.1–10 THz (wavelength of 3 mm-30 𝜇𝑚) has
progressed [Lee 2009] and called "Terahertz" region. Electromagnetic waves of these frequencies can penetrate various materials
such as paper, plastic, fibers, and semiconductors. The researchfor applications in the terahertz range is actively being conductedin several fields, such as PoS systems [Willis and Wilson 2013],
foreign substance inspection [LEE et al. 2012], communication [Federici and Moeller 2010], medical sensing [Siegel 2004], and more.
However, limited commercial applications exist for terahertz range
waves [Banerjee et al. 2008]. Frameworks and design methods arerequired for identifying practical, everyday applications for computer human interactions.
To realize a simple pipeline in the terahertz region, we proposed
TeraFoils—which helps create a material-like holographic structure by attaching a silver foil to paper—applying the technique ofcreating electronic circuits using silver foil [Segawa et al. 2019].
Using a home-use laser printer and an electric iron (as shown inSIGGRAPH ’21 Posters, August 09-13, 2021, Virtual Event, USA

Fabrication Process
Printed Paper

Simulation & Result

2

Input

1

Backward
Propagation

4

Simulated3

ForwardPropagation
Amplitude Hologram
Plane: f2(x,y)

IronSilver Foil

Binarization

Fabricated

Image Plane:g1(x,y)BrushReconstructed
Image: g2(x,y)

Captured

Hologram Calculation
Amplitude Hologram
Plane: f1(x,y)

Yamamoto et al.

Figure 2: Left: designing an amplitude-modulated hologram. Center: fabrication flow. Right: results of our method (SIG letter).
Fig. 2), we achieved a faster and more economical method thanthat employed in a 3D printer. Wave propagation calculations wereperformed to design a binary amplitude hologram, and the designed
hologram pattern was simulated. With the designed pattern, paperand silver foil were used to produce holographic structures, andtheir functions were confirmed with the experimental setup shownin Fig. 1.

2

PROPOSED METHOD AND RESULTS

Light wave propagation was calculated to design a binary amplitude
hologram and simulate the reconstructed image from the hologram
pattern, as shown in Fig. 2 (left). First, light wave back-propagatesfrom the image plane 𝑔1 (𝑥 1, 𝑦1 ) to the hologram plane 𝑓1 (𝑥 2, 𝑦2 ) asfollows:  𝑖𝜋𝑝 2  2
𝑓1 (𝑥 2, 𝑦2 ) = F −1 F [𝑔1 (𝑥 1, 𝑦1 )]F exp
𝑥 1 + 𝑦12. (1)𝜆𝑧Next, a binary amplitude hologram 𝑓2 (𝑥 2, 𝑦2 ) is calculated by binarizing the amplitude of the propagated plane:
𝑓2 (𝑥 2, 𝑦2 ) = 𝑏𝑖𝑛𝑎𝑟𝑖𝑧𝑒 (𝑓1 (𝑥 2, 𝑦2 )).

(2)

The propagation calculation is performed again using Eq. 1, andthe reconstructed image 𝑔2 (𝑥 1, 𝑦1 ) is derived to simulate the image
reconstruction with the binary amplitude hologram.
A hologram structure is fabricated by thermo-compression bonding silver foil to paper on which the designed pattern is printed
with ink, as shown in Fig. 2 (center). The fabricated hologram, theactual propagation result, and the simulation results are shown inFig. 2 (right). The actual propagation result is captured by moving
a two-dimensional THz sensor on the XZ stage, as shown in Fig. 1.
Although the actual propagation result is noisy, the experimental
results are in agreement with the simulation results.

3

CONCLUSION AND FUTURE WORKThis paper proposed a design and manufacturing method for TeraFoils. In this method, a structural design is obtained based onhologram calculation, and thermo-compression bonding of silver
foil is used for the fabrication process. Because silver foil does
not transmit terahertz waves, the hologram must be binarized. The

designed holographic structure was created, and the propagation result was confirmed using a two-dimensional THz sensor. Although
there was noise in the image after propagation, we could obtain
results similar to those of the simulation.
However, some improvements can be made in the future. First,
the accuracy of the hologram should be improved via optimization.
Second, concrete applications should be created using this method.
We believe that such improvements can further contribute to TeraFoils as a rapid fabrication method for new holographic structuresin the terahertz region.

ACKNOWLEDGMENTS
The authors would like to thank laboratory students (Keita Yamazaki, Tatsuya Minagawa, Masaaki Sadasue, Daichi Tagami, andIppei Suzuki) for their valuable comments and their help with theexperiment. This work was supported by JSPS KAKENHI Grant
Numbers JP17H04688.

REFERENCES
D. Banerjee, W. von Spiegel, M. D. Thomson, S. Schabel, and H. G. Roskos. 2008.
Diagnosing water content in paper by terahertz radiation. Opt. Express 16, 12 (Jun2008), 9060–9066. https://doi.org/10.1364/OE.16.009060
John Federici and Lothar Moeller. 2010. Review of terahertz and subterahertz wirelesscommunications. Journal of Applied Physics 107, 11 (2010), 111101. https://doi.org/10.1063/1.3386413 arXiv:https://doi.org/10.1063/1.3386413
YOUNG-KI LEE, SUNG-WOOK CHOI, SEONG-TAE HAN, DEOG HYUN WOO,and HYANG SOOK CHUN. 2012. Detection of Foreign Bodies in Foods
Using Continuous Wave Terahertz Imaging.
Journal of Food Protection 75, 1 (2012), 179–183.
https://doi.org/10.4315/0362-028X.JFP-11-181
arXiv:https://jfoodprotection.org/doi/pdf/10.4315/0362-028X.JFP-11-181
Yun-Shik Lee. 2009. Principles of Terahertz Science and Technology. Springer US. –pages. https://doi.org/10.1007/978-0-387-09540-0
Norihisa Segawa, Kunihiro Kato, and Hiroyuki Manabe. 2019. Rapid Prototyping ofPaper Electronics Using a Metal Leaf and Laser Printer. In The Adjunct Publicationof the 32nd Annual ACM Symposium on User Interface Software and Technology (NewOrleans, LA, USA) (UIST ’19). Association for Computing Machinery, New York,NY, USA, 99–101. https://doi.org/10.1145/3332167.3356885
P. H. Siegel. 2004. Terahertz technology in biology and medicine. IEEE Transactions on
Microwave Theory and Techniques 52, 10 (Oct 2004), 2438–2447. https://doi.org/10.
1109/TMTT.2004.835916
Karl D. D. Willis and Andrew D. Wilson. 2013. InfraStructs: Fabricating Information
inside Physical Objects for Imaging in the Terahertz Region. ACM Trans. Graph. 32,4, Article 138 (July 2013), 10 pages. https://doi.org/10.1145/2461912.2461936