CSEM - Resonant Diffractive Optics for Augmented Reality

Resonant Diffractive Optics for Augmented Reality Guillaume Basset
CSEM SA
2
CSEM: A public-private partnership
• A not for profit private company •Industry friendly IP approach
14 %
Swiss Governement
13 %
Neuchâtel –City & Canton
73 %
Private Organizations
shareholding
3
CSEM mission
Development and transfer of world-class (micro-)technologies to the industrial sector –in Switzerland, as a priority –in order to reinforce its competitive advantage.
•Cooperation agreements with established companies •
Encouraging the creation of start-ups
4
CSEM at a glance
437
Persons
43
New ventures
175
Industrial clients
203
Patent families
64
European projects
43
Nationalities
83.0
Turnover (MCHF)
5
Close to industry , leveraging Swiss academic research
N N A L M Z
N
A
L
M
Z N CSEM Zürich
CSEM Muttenz
CSEM Neuchâtel
CSEM Alpnach
CSEM Landquart
CSEM Brasil
Augmented Reality Optics at CSEM
7
Diffractive Exit Pupil Expander and Combiner with high RI
Diffractive waveguide with 2D exit pupil expansion in refractive index > 1.78
Nano imprint lithography of high refractive index materials
In-coupling gratings
Out-coupling gratings
Second grating (EPE)
HRI glasses waveguides
8
Chemistry of photosensitive TiO 2sol-gel materials
From photosensitive HRI sol-gel materials to Nano-imprinted HRI sol-gel materials
•Properties of the TiO 2sol-gel materials
Sol (MeOH + EtOH)
TiO 2
/ BzAc
Spin coating Dip coating
TiO 2/ BzAc xerogel (soluble in EtOH)
Development in EtOH
Structured TiO 2
UVA
BzAc degraded
TiO 2xerogel (insoluble)
Heat treatment
Structured TiO 2anatase phase
V. Gate, PhD thesis, University Jean Monnet, Saint-Etienne, 2013.
V. Gate, Y. Jourlin, F. Vocanson, M. Langlet et al,Sub-micrometric patterns written using a DIL method coupled to a TiO 2photo-resist,
Opt. Mater.2013, 35, 1706-1713.
9
UV Imprint & Calcination
From photosensitive HRI sol-gel materials to Nano-imprinted HRI sol-gel materials
Refractive index & Imprint depth
vs.
Calcination temperature
Before
calcination
After calcination
Optical properties of
Meta-Resonant Waveguide-Gratings
11
Resonant Waveguide-Grating
12
Idea: Merge two RWGs by
multiplexing at least two spatial frequency →Color selective diffraction in any configuration
(free-space of waveguide)
→Can replace Surface Relief Gratings (SRGs)
→Manufacturing similar to SRGs (NIL)but more advanced origination (e-beam)
+ a thin film coating
Meta-Resonant Waveguide Grating
Example of E-beam master –Periodic structures
(deeply subwavelength structures)
13
Scale comparison of Meta-RWG
Smaller structures than SRGs, similar size to
dielectrics meta-surfaces But low aspect ratio
14
Measurement of Green medium bandwidth Diffraction
70°off-normal incidence diffracted to normal
→Extremely high transmission, great see-through Subwavelength structures →
Very low stray light
15
Bandwidth of diffraction is largely tunable
Light incidence 75°off normal in air: ~38°in a std glass, diffraction to normal Simulation results –Optical metrology of fabricated devices are confirming the tunability
Diffraction bandwidth tunable from >20nm to <0.2nm (525nm)From >4% of λto <0.04% of λ
Meta-RWG Free-Space Combiner with very large FOV
17
Why free-space combiners?
Single color prototype Multiple exit pupils missing Very small Eye-box!
Free-space combiners can be curved, thin, lightweight, have no intrinsic FOV limitation –but the eyebox is a real issue
18
Meta-RWG as free-space combiners
Wavelength multiplexing
(and/or angular multiplexing)→Multiple exit pupils →Active foveation
Very-large FoV (>80°horizontal)Ellipsoidal-mirror function
→Keeping wavefront curvature →Compatible with
holographic projection Combiner can be curved
and have any shape
No/Very low parasitic rainbow-effect
19
Capabilities of MRWG Free-Space Combiners
✓Lightweight & compact ✓Curved / non-flat combiners ✓Very large FoV, no limiting RI ✓Very high transparency ✓Fully passive
✓Holographic or Multifocal
✓Foveated display (active/static)✓Higher efficiency than passive 2D EPE (~100 pupils)
✓Affordable & high volume?
❑To be demonstrated: Multiple Pupils –Active Foveation -Large Eyebox
❑To be done: Integration with microdisplay and imaging
optics, alignment/mechanics tolerancing
CSEM is developing new optical solutions for Augmented Reality pending requirements
Contact us: gba@csem.ch www.csem.ch。