3 D Display: Current and future technologies in Europe

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3 D Display Current and future technologies in
Europe
Part 2 3D Display Research at DMU Phil
Surman Wing Kai Lee Imaging and Displays
Research Group De Montfort University Leicester
UK
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Presentation

• Principle of operation of DMU display
• ATTEST multi-user 3D prototype
• MUTED 3D display project
• Future work

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PRINCIPLE OF OPERATION of DMU Display
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DMU Display
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Exit Pupils
PLAN VIEWS
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Exit Pupil Formation
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Multiple Exit Pupil Formation with a Lens
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Exit Pupil Formation with Array

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Exit Pupil Steering
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Exit Pupil Steering
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Exit Pupil Steering
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Coaxial Optical Element

• Illumination and refracting surfaces both
  cylindrical with common vertical axis
• Aperture centred at axis
• No off-axis aberrations
• Light contained in element by total internal
  reflection

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Collimated Beam Formation
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Spatial Multiplexing
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Spatial MUX with Parallax Barrier
Parallax barrier
Illumination sources
LCD
L
R
L
R
SIDE VIEW
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Spatial MUX with Lenticular Screen
Lenticular screen
Illumination sources
R
L
L
R
SIDE VIEW
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First Prototype
Screen assembly
Upper mirror
R
L















Light sources
Lower mirror
This prototype has fixed pupils its purpose is
to demonstrate spatial multiplexing
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First Prototype
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Early Work Schematic Diagram from PhD

Multiplexing screen (Ch.5)
IR camera (Ch.12)
LCD (Ch.6)
Illumination source (Chs.910)
Vertical diffuser (Ch.7)
Head tracking processor (Ch.12)
Fresnel lens (Ch.3)
Exit pupils (Ch.3)
R
L
Viewer (Ch.8)
Folding mirrors (Ch.4)
Viewing field (Ch.8)
Retro- reflector (Ch.12)
FIG.1.1 SCHEMATIC DIAGRAM OF PROTOTYPE 3D
DISPLAY
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Early Work Head Tracker
LED array showing head position
IR diodes and camera lens
Head
Retro-reflector
FIG.12.1 HEAD TRACKING SET-UP
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Early Work Head Tracker
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Early Work Moving Illumination Source

Stepper motor
Pinion
Magnet
Track
Rack
Wheel
Left halogen aperture
Right halogen aperture
Wheel
Reed switch
FIG.10.2 HALOGEN LAMP ILLUMINATION ASSEMBLY
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ATTEST PROTOTYPE
CONSTRUCTION AND RESULTS
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ATTEST Array Element and Illumination/Driver
Board
Soft Aperture

• Aperture printed on strip of film (RH figure)
• 2 aperture components cemented together with
  aperture in between

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ATTEST Array Element and Illumination/Driver
Board

• This shows first version with 90 x 3mm white
  LEDs.
• Exit pupils move in large increments (30mm)

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ATTESTLCD Diffraction
ATTEST Illumination/driver Board Version 1
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ATTEST Illumination/driver Board Version 2

• 256 x 1 mm surface-mount white LEDs
• Comprises 16 x 16-element modules

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ATTEST LED Module

• 16 x 1 mm surface-mount white LEDs
• Integral driver and heat sink

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ATTEST Illumination Sources

• This shows collimated beams formed in different
  directions
• Beam width can be increased by lighting more
  LEDs

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ATTEST Multiple Exit Beams

• Multiple beams formed by lighting several sets of
  adjacent LEDs

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ATTEST DemonstratorArray

• Constructed for demonstration of multiple exit
  pupil formation but without use of LCD

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ATTEST Demonstrator Exit Pupils

• Beams formed on targets.
• Polhemus electromagnetic tracker pickups located
  at targets

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ATTEST Array Configuration

• One ten-element array is used for each of the
  left and right sets of exit pupils
• comprises two sets of five staggered elements

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ATTEST Appearance of Front of Array
Continuous illumination over this width

• Aperture images are effective LCD backlight
• Vertical diffuser required to enable aperture
  images to illuminate full LCD height

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ATTEST Soft Apertures

• Soft apertures allow for constructional errors
  and aperture image width variation
• Fading width determined from trials on perception
  of brightness variation

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ATTEST Aperture Intensity Variation
(a) Appearance of aperture images
Relative intensity
(b) Intensity variation
Distance across array
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ATTEST Folding Mirrors
PLAN VIEWS
Virtual image
Mirror
Steering optics
Steering optics
Mirror
Virtual image
(a) Without Folding
(b) With Folding

• Virtual arrays formed either side of actual
  array
• Reduces housing size

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ATTEST Folding

• 5 Mirror folding enables same housing size as
  current rear projected displays (side mirrors not
  shown)

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ATTEST Prototype
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ATTEST Plan view of Prototype
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ATTEST Prototype Side Elevation
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ATTEST Prototype

• Incorporates same large optical elements as used
  in demonstrator
• Large cylindrical convex in front of LCD to
  increase brightness

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ATTEST Display Sub-pixels

• 15µM structure within RGB sub-pixels

RGB Sub-pixels

• Very high first-order component

Diffraction
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ATTEST LCD Diffraction

• Vertical diffraction ltlt horizontal diffraction

• large first order gives 15 crosstalk

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ATTEST Exit Pupil Profile

• Maxima produced by use of discrete components
• Left eye located at position L
• Right eye located at position R
• Profile is convolution of aperture function with
  diffraction function (PSF)

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ATTEST White LED Colour Variation

• Blue region shows total variation from
  manufacturer
• This region divided into four
• Even with LEDs from one batch, variation still
  large

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ATTEST Further Work Identified

• Use LCD with suitable sub-pixel structure to
  minimise diffraction
• Select appropriate material and manufacturing
  process to minimise scattering
• Use single illumination source to illuminate
  colour and brightness variation
• Use low etendue illumination source to reduce
  light loss
• Reduce housing size - consumer preference is for
  hang-on-wall
• Develop multi-user non-intrusive head tracker

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MUTEDMulti-user Three-dimensional Television
Display
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MUTED Brief Summary

• EU-funded
• Kicked-off July 2006
• 30 months duration
• 30 person years of effort
• 7 partners including SLE and Fraunhofer HHI

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MUTED Technical Summary

• RBG laser illumination source
• Provides wide colour gamut
• Holographic projector-controlled exit pupils
• Developing multi-user non-intrusive head tracker
• Human factors issues examined
• Investigation into low-diffraction LCD
• Investigation into temporal MUX
• Exploitation of display in medical applications

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MUTED Semi-coaxial Array

• Array elements have flat back surface hence
  semi-coaxial
• Enables other means of illumination, for example
  projection

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MUTED Optical Array
Illumination in this plane
Light from projector
Light to screen assy.
SECTION OF ARRAY
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MUTED Illumination Plane

• Each exit pupil position can be mapped to a
  diagonal series of small sources
• Slope of diagonal determines exit pupil distance
  and lateral position the x-co-ordinate

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MUTED Optical Array
HOLOGRAPHIC PROJECTION

• Conventional projection blocks of 95 of light
• Use of CGH projector utilises complete wavefront
  on LCOS SLM
• Binary phase hologram gives around 40
  efficiency
• Investigating use of conjugate image to double
  efficiency

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MUTED Schematic Diagram
RGB LASER
HEAD TRACKER
LCOS
LCD
OPTICAL ARRAY
MOBILE VIEWERS
SIMPLIFIED SCHEMATIC DIAGRAM OF DISPLAY
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MUTED Current Status

• Investigation into aperture-less optical elements
  for simplified construction
• Refining LCOS algorithms
• Measurement of suitable LCD panels wrt to speed
  and diffraction
• Deciding multi-user tracker route
• Low power monochromatic version under construction

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MUTED Enabling Technologies
MUTED completed
MUTED
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MUTED Display Performance
MUTED
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FUTUREWORK
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Future Work

• European Union Framework 7 round of funding
  started in December 2006
• First Call closes 8th May 2007
• Multi-user 3D displays included in call
• Also high colour gamut
• Interactivity supported

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Extract from EU Workplan

• Advanced visualisation systems and novel
  display technologies.
• Visualisation systems extending colour gamut
  and dynamic range beyond current
  state-of-the-art, taking into account human
  vision and perceptual models. They should support
  multi-viewer, unaided and unrestricted 3D
  viewing, as well as natural interaction
  modalities. This includes signal acquisition,
  processing and representation technologies for
  3D-systems.

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High Efficiency Laser-based Multi-user
Multi-modal 3D Display (HELIUM3D)

• Direct-view laser-based 3D display to be
  developed
• Does not require LCD
• Image information supplied by light valve
• Illumination source is RGB lasers.
• High colour gamut
• Direct-view
• Does not have light attenuation of LCD - energy
  efficient
• Frees reliance on LCD fabrication plants

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HELIUM 3D Schematic Diagram
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HELIUM 3D Colour Gamut
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HELIUM 3D Display Functionality

• Display is functionally scalable
• Fast light valve speed could enable a different
  image to be seen by each eye in viewing field
• Enables motion parallax
• Each viewer could choose their desired viewpoint
  if scene captured by a camera array
• Each viewer could see completely different images
  to other viewers
• Display will work in near field and far field
  modes

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HELIUM 3D Near Field Operation

• Screen around 1 1.5 metre from viewer
• Immerse hands into image therefore image 0.5
  m from user
• 1 or 2 users, single or collaborative working
• Large disparities up to I/O distance
• Large convergence/accommodation rivalry (human
  factors work necessary)

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HELIUM 3D Near Field Tracking

• Requires low tracker latency high latency will
  affect task performance and could cause nausea
• Requires high tracker accuracy (more than for
  just locating exit pupils)
• Head tracking in x, y and z directions
• Images rendered in accordance with head
  co-ordinates

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HELIUM 3D Near Field Example

• Virtual Clay concept - clay shaped with naked
  hands
• A virtual chunk of clay floats in front of screen
• Touching and shaping the clay with the naked
  hands enables user to directly manipulate object
• Approach completely differs from existing
  techniques - perceptual space matches interaction
  space
• This technique potentially useful in medical task
  applications

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HELIUM 3D Far Field Operation

• Viewing distance around 2 4 metres
• Gaming
• Television
• Videoconferencing