디지털홀로그래피연구실 한국전자통신연구원 (ETRI). 홍기훈_발표... ·...

홍기훈

디지털홀로그래피 연구실한국전자통신연구원 (ETRI)

2019. 11. 6. 2019국제저작권기술콘퍼런스

2앞서가는 ICT, 보다 나은 세상, 함께하는 ETRI

ContentIntroduction

Hologram? Holography?

Digital holography

Basic principle of holography

Issues on digital holographic display

Related research in ETRI

Digital holographic display

Digital holographic media service

INTRODUCTION



What is not a hologram?

1977 Star wars



2008 U.S. election, CNN



2012, Coachella Valley Music and Arts Festival 2014, k팝 홀로그램 공연장


Pseudo-hologram (유사홀로그램)

Pepper’s Ghost Illustration of the Pepper’s ghost illusion during the 1862 production ofCharles Dicken’s play The Haunted Man.


Pseudo-hologram (유사홀로그램)

IBTimes(2012, http://img.ibtimes.com/www/data/images/full/2012/04/17/263787.jpg)



Holographic Wife Offers Intimacy to Japan's Celibate GenerationMirage 3-D Instant Hologram Maker



Science fiction Pseudo-hologramHologram:

optical element or display

DIGITAL HOLOGRAPHY


Issues on digital holographic display



Holo + Graphy

From …

• The Greek ὅλος hólos, "whole" + γραφή grafē, "writing, drawing“

Means …

• Recording of full characteristics of the light

– Both amplitude and phase of the light


Basic principlesHologram Recording

Generate a laser light and split into two wavefronts,

• Reference beam + Object beam

The hologram is recorded with interference fringe pattern of two

wavefronts

Holographic 3D Image reconstruction

Diffracted light from the interference fringe hologram by coherent

reference light

HologramRecording

ImageReconstruction

Beam Splitter

Laser Light

mirror

Reference

beam

object

Objectbeam

Photosensitivefilm

Interference pattern(hologram)

Virtual image

Hologram

viewer

Laser Light


Key history

Dennis Gabor (1948)“A new microscopic principle,” Nature 161 (1948)• Proof of concept : Holography as “whole light-field recording”

• On-axis hologram, no Laser, twin-image problem

Awarded Nobel Prize in Physics (1971)

E. N. Leith and J. Upatnieks (1962)“Reconstructed wavefronts and communication theory,”(1962)• 1st demonstration of 3D imaging … Off-axis hologram

• Used Laser(invented at 1960) as a light source

Y. N. Denisyuk (1962)“Photographic reconstruction of the optical properties of an object in its own scattered radiation field,” (1962)

White-light reflection holography

Stephen Benton (1968)“Color images with the MIT holographic video display," (1992)• Pioneered electro-holography for moving 3D image representation

Stephen A Benton(1941-2003)

Yuri N. Denisyuk(1927–2006)

Dennis Gabor(1900–1979)

Emmett Leith(1927–2005)


Photography vs. Holography

PhotographyCamera with lens

• Principle of Pin-hole camera

Records the light intensity

• A pixel records an integration of light rays reflected from a point of the scene

– Loose the ray path information

– Records only the light intensity

Holography Is a lensless photography

• A pixel records an integration of the wavefront

reflected from every point of the scene

– Keep all the wavefront information (amplitude & phase)

• Needs a reference beam of coherent light

P1H1(everywhere)

Film

P2

H2

P1I1(point)

Film

P2

I2


Photography vs. Holography

1972, Introduction To Holography


Examples of analog hologram

http://www.ultimate-holography.com

Hologram movie??


Digital holography

Hologram generation Analog: Optical recording with holographic film

Digital: Optical recoding with CCD

Computer generated hologram (CGH)

Hologram reconstructionAnalog: Optically recorded hologram

Digital: Spatial light modulator (SLM)

Digital, computational, electronic holography

Reference wave

Diffracted light

Computer

CGH

Recording: CCDReconstruction: SLM


Analog vs. Digital holography

아날로그 홀로그램

생성/기록

/디스플레이

편집

디지털 홀로그램

광학계/필름 CCD/SLM/컴퓨터

전송

편집 불가 편집 용이

압축/전송 불가 압축/전송 용이

유연성

용이성

용이성


Issues on digital holography: Display

Core components

SLM

• For highly efficient complex modulation of light

Coherent light source

Requirements on SLM

Pixel pitch of about wavelength

of the light

Large size for large image

Large SBP

(Space Bandwidth Product)



Image size, viewing angle/zone, depth range

Depends on the specification of SLM

Viewing

angle

Image size/

resolution

Expressible

depth range

Viewing

zone

SLM



Number of pixel: N×MSLM

Diffraction angle: θ

Pixel pitch: p

Wavelength: λ

Space bandwidth product (SBP)

Diffraction angle

SLM size

𝜃 = sin−1𝜆

2𝑝

𝑆 = (𝑁×p)×(𝑀×p)

Trade-off!

Pixel pitch (p) Viewing angle (𝜃) Resolution (MxN)

32 µm 0.48˚ 3k × 3k

8 µm 1.91˚ 12k ×12k

1 µm 15.43˚ 100k × 100k

0.5 µm 32.16˚ 200k × 200k

Ex. 10x10 cm2 size SLM with 𝜆=532 nm


Issues on digital holography: Contents

Direct hologram acquisition

LaserRequires coherent light source, laser

Restricted to lab environment

Low resolution, color, real time issues

Safety?? Outdoor??


Issues on digital holography: Contents

ddyxz

kjU

zj

eyxU i

jkz

o 2

exp,,22

Fresnel

diffraction

ddr

jkrU

j

zyxU

exp,,

2

01

01

First Rayleigh-

Sommerfeld

formula

yxyxyxyxyx dfdfyfxfjffcircffz

jffAzyxU

2exp1

2exp0;,;,

2222Angular-

spectrum

Computer generated hologram

Computational load!! Real-time??

RELATED RESEARCH IN ETRI

Digital holographic display

Digital holographic media services


360 degree holographic display: Motivation

The beginning.. Princess Leia!!

360˚

Three-dimensional image

Large image size

Natural color

Movie

Midair display (Tangible)

Interaction

For many viewer

And… high image quality


360 degree holographic display

< system 1> < system 2> < system 4> < system 5> < system 6>

236 mm

133 mm

234 mm

L=215 mm

H= 215 mm

305 mm

50 mm(영상면 직경)

System 1 System 2 System 3 System 4/5

Resolution of DMD 1,024 × 768 1,920x1,200

Spatial multiplexing (tiling) 2 × 2 - 2 × 1 -

Resolution after tiling 1,536×1,536 768×768 1,024×1,024 1,200x1,200

Color × ○ ○ ○Magnification 2.7 5.1 5.1 6.4/4.2

Image size(diag.) [inch] 3.16 2.98 3.98 4.6/3.0

Number of viewpoints 434 1,024 1,024 1,024

Total data rete [Gbps] 20.5 36.2 128.9 88.5


360 degree holographic display

세계 최초의 360도 컬러 홀로그램 동영상 재현

실사 기반 hologram images : Guitar man (right, front, left, back viewpoints)


Positioning of ETRI’s display

D. Blinder, et al., Signal processing challenges for digital holographic video display systems, Signal Processing: Image Communication (2018),https://doi.org/10.1016/j.image.2018.09.014

Head-mounted holographic displays will thus most likely be the first kind of holographic displays that will be available to consumers in the near future.

SUDD is projected to mature shortly after head-mounted displays are commercially available, because many of the challenges overlap.

MUD are highly useful when multiple users need to simultaneously observe and interact with 3D models, especially over long periods of time, enabling applications in design, manufacturing, medicine, sports, etc.



Digital holographic media service model

자연광 기반 홀로그램 직접획득, 초고해상도 홀로그램 실시간 생성/변환 렌더러, 동영상 홀로그램 코덱

Data Acquisition

Hologram Acquisition

Compression

Hologram Compression

R/G/B Hologram

Meta Data

Transmission

Broadcasting

Network

Storage

Decompression

Hologram Decompression

Device

Holographic Display

One-way Channel

Renderer

3D Display

R/G/B Hologram

Meta Data

3D Image Acquisition

Renderer



Direct hologram acquisition

자연광 기반 실시간 홀로그램 직접 획득

SIDH GP-SIDH Complex hologram

자가간섭광학계

위상변조광학계 CCD

자연광

실시간

K. Choi, J. Yim, and S. Min, Opt. Express 26, 16212-16225 (2018).



Ultra high resolution hologram generation

256 level

2-level (Binary)

High resolution Hologram PoC- 40K x 40K resolution

- 500 nm pixel size

- 20 x 20 mm2 total size


QnA

Thank you for your attention.

감사합니다[email protected]

mailto:[email protected]

디지털홀로그래피연구실 한국전자통신연구원 (ETRI). 홍기훈_발표... ·...

Documents

Transcript of 디지털홀로그래피연구실 한국전자통신연구원 (ETRI). 홍기훈_발표... ·...