Supplementary Material
Image jitter enhances visual performance when spatial resolution is impaired
Lynne M. Watson1, Niall C. Strang1, Fraser Scobie2, Gordon D. Love2,
Dirk Seidel1, Velitchko Manahilov1
1Department
of Vision Science, Glasgow Caledonian University, UK
2Department
of Physics, Durham University, UK
Contents
Figs. S1-S2
Table S1
1
Table S1. Data for the visually impaired subjects who took part in this study. VA (distance
visual acuity), LogMAR (logarithm of the minimum angle of resolution), CS (contrast
sensitivity), CSS (central scotoma size, as measured on an Amsler chart), LP – light
perception; X – not recordable, CE – Control Experiment 2..
Subj.
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
VA
(LogMAR)
Right Left Both
1.40
1.67
0.60
1.30
1.20
1.70
1.90
1.30
1.80
1.80
1.80
0.60
0.60
0.70
1.30
1.10
1.20
1.80
1.0
2.0
1.44
1.40
1.70
1.00
0.88
0.80
1.10
1.10
0.70
0.40
1.30
2.00
0.90
0.70
LP
1.20
1.80
1.80
1.50
0.90
1.20
1.12
1.40
1.67
0.70
0.90
0.88
1.10
1.10
0.70
0.40
1.30
1.80
0.60
0.60
0.70
1.20
1.10
1.20
1.50
0.90
1.20
1.12
Right
n/a
0.75
n/a
n/a
n/a
0.75
0
0
0
0.3
0.60
1.35
1.25
1.10
0.50
1.20
1.50
0.60
1.20
0.60
1.50
CS
(log units)
Left Both
n/a
0.75
n/a
n/a
n/a
1.20
1.05
1.05
1.35
1.35
0
1.20
1.20
X
0.40
1.30
1.70
0.80
1.20
0.40
1.05
n/a
0.75
n/a
n/a
n/a
1.2
1.05
1.06
1.35
1.35
0.60
1.20
1.20
1.10
0.40
1.20
1.50
0.80
1.20
0.40
1.05
CSS
(deg)
Right Left
10
12
3
n/a
5
16
15
6
12
10
15
3
5
5
6
5
8
6
5
14
8
10
10
4
n/a
4
10
5
5
4
8
15
5
5
LP
6
14
10
6
5
6
4
Age
(yrs)
Gender
Experiment
83
62
68
82
77
84
86
85
76
73
80
78
80
76
75
78
80
74
79
90
80
F
M
F
F
F
M
M
F
F
F
F
M
F
F
M
M
F
F
F
M
F
CE2
CE2
CE2
CE2
CE2
1,2,3
1,2
1,2,3
1,2,3
1,2
1,2
1,2,3
1,2,3
1,2,3
1,2
1,2
CE2,1,2
CE2,2
C2,1,2
2
2,3
2
Apparatus
In Experiment 4, the image jitter was produced by a monocular prototype of jitter
goggles. The prototype utilizes Wollaston prisms and ferroelectric liquid crystal (FLC)
polarization modulators. A Wollaston prism consists of two orthogonal birefringent prisms
cemented together (Supplementary Fig. 1). Their optic axes are perpendicular to each other
and perpendicular to the direction of the incident light. Unpolarized light, incident on a
birefringent material, is refracted into an ordinary ray (Supplementary Fig. 1, O-ray),
polarized perpendicular to the optic axis, and an extra-ordinary ray (Supplementary Fig. 1,
E-ray), polarized parallel to the optic axis. Both rays travel through the first section
undeviated, due to the optic axis being perpendicular to the direction of the incident ray,
with the extra-ordinary ray travelling slightly faster than the ordinary ray. As the optic axis
of the second prism is perpendicular to the first the ordinary ray becomes the extra-ordinary
ray and vice-versa. At the point of incidence the extra-ordinary ray is refracted away from
the normal of the plane interface while the ordinary refracts toward it. The angle of
divergence of the two rays is dependent on the wedge angle of the prisms.
The complete optical system contained two Wollaston prisms to produce four
possible image positions (Supplementary Fig. 2). The second prism was rotated by 90 deg
such that the plane of divergence is perpendicular to that of the first prism. Unpolarized light
becomes plane polarized to prevent the optical system from producing multiple images. The
direction the light is refracted when passing through the Wollaston prism is dependent on
the state of the FLC. The FLC acts as a switchable half-wave plate that controls whether the
polarization of the light passing through is rotated (90 deg) or unchanged. The light will
therefore follow either the path of the ordinary or extra-ordinary ray as shown in
Supplementary Fig. 1. The state of the second FLC is independent of the first such that after
3
passing through the first Wollaston prism there are again two possible paths the light can
take. When an FLC changes state, the light path will change and consequently the image
position. If the FLCs change state at high speed the change in image position will be
perceived as jitter. The angular size of the square, formed by the four ray paths, was
1.8x1.8±0.1 deg with the total transparency of the system being 20±0.1%.
Figure S1. The figure shows the paths that the extra-ordinary (E-ray) and ordinary (O-ray)
rays take as they pass through the Wollaston prism and how they both travel at the same
angle away from the direction of the incident (I) ray.
4
Figure S2. Illustration of the full setup used to create image jitter. By combining two
Wollaston prisms with independently controlled ferroelectric liquid crystals (FLC) it was
possible to create four image positions. The path an incident ray will take is dependent on
the state of the two FLCs. The different colors are designed to clarify the ray paths and
image positions and do not imply any wavelength separation.
5