Download Presentation

Multifocal method
using Liquid Crystal
Xuan Wang
Oct, 28th
Multifocal method using Liquid Crystal
 High-speed switchable lens enables the development of a
volumetric stereoscopic display. Love, Gordon D., et al. Optics
express 17.18 (2009): 15716-15725.
 A multi-plane optical see-through head mounted display design
for augmented reality applications. Liu, Shuxin, Yikai Su et al.
Journal of the Society for Information Display 24.4 (2016): 246-251.
 Fast-response switchable lens for 3D and wearable displays.
Lee, Yun-Han, Fenglin Peng, and Shin-Tson Wu. Optics express
24.2 (2016): 1668-1675.
High-speed switchable lens
• High-speed switchable lens enables the
development of a volumetric stereoscopic display
They present a new stereoscopic display system using a high-speed,
switchable lens integrated with computer display.
The lens is placed in front of the eye and is synchronized to the
graphic display such that each depth region in the simulated scene is
presented when the lens is in the appropriate state. In this way, they
construct a temporally multiplexed image with correct focus cues.
High-speed switchable lens
• Key Element
• 1 Polarizer
• 2 Birefringent
lenses
• 2 Liquid Crystal
Modulators
High-speed switchable lens
• Lens Performance
The four focal
states are shown.
The distance:
(a) 285 mm
(b) 375 mm
(c) 590 mm
(d) 970mm
High-speed switchable lens
• Setup
High-speed switchable lens
• Results
High-speed switchable lens
• A multi-plane optical see-through head mounted
display design for augmented reality applications
They presented a design for an optical see-through HMD
utilizing multiplane display technology.
Polymer-stabilized liquid crystal scattering shutters were used
in projecting slices of a 3D scene. A proof-of-concept
two-plane optical see-through HMD prototype is demonstrated.
High-speed switchable lens
• Polymer-stabilized liquid crystal scattering shutter
High-speed switchable lens
• Setup
High-speed switchable lens
• Results
Fast-response switchable lens
• Fast-response switchable lens for 3D and wearable
displays
They presented a focus-switching device for 3D head mounted
displays. A twisted nematic (TN) cell liquid crystal is used as
polarization switch to control the optical path length through the
system. Different polarization state leads to different path length in
the proposed optical system, which in turn results in different focal
length.
They also proposed some configuration to cascade such device
structures together to generate more different focuses for 3D
displays.
Fast-response switchable lens
• Key Element
The LC device used here is a
90°twisted nematic (TN)
cell. This is an electrically
tunable achromatic half-wave
(λ/2) plate.
For a linearly polarized input
light, say p-wave, the output
light can be converted to swave if the applied voltage is
off (V = 0) or it remains pwave if V>>Vth (threshold
voltage).
Fast-response switchable lens
• Experimental setup
The total path length
from L1 to L2 for the
red route is d1 = 43
cm.
The total path length
from L1 to L2 for the
blue route is d2 = 48
cm
Fast-response switchable lens
• Results
Fast-response switchable lens
• Features
• Response time
• The rise time and the decay time to be 4.3 ms and 1.0 ms, respectively.
Note that the response time was not optimized due to the limited TN
cells they have. (the rise time and the decay time can reach 2.8 ms and
0.6 ms theoretically)
• Voltage
• The power they use is an AC voltage(1kHz) of only 10V, which is safe
for human.
• Low chromatic aberration
• PBS, TN and retardation plates are all achromatic
Fast-response switchable lens
• Configuration
Thank you!