PHYSICS SECTION '62
for 2 u ' < 0. 8 rad (¡=45°). . . . . . mm
used with spectacles mm
Low Mi
High M2
Ratio M2/M1
1 of 23 x 23 Cm2 print) at Mi
at M2
Concentricity of areas (in % r 2)
"Optical axis" angle with perpendicular on print mrad
Eye-base + range of adjustment mm
Separation between corresponding points on prints cm
Parallax adjustment for height differences Ax cm
Differences in Magnification between right and left (% or A y) mm
Model-curvature by Distortion (subjective)
Rotation of one image to the other (milli-radians)
Re-orientation when changing M2 -» Mi: A y mm
: rotation mrad
Observed area of stereo-model (in % of A (point 4))
Scanning and Double Scanning
Scanning : parallel shifting of
Parallax adjustment: Ay (mm) (Ax is less critically)
•Y-parallax introduced by non-parallel scanning ....
Total area which can be scanned
"Optical axis" angle with _L on print when scanning . .
Image Recording
Size of exit pupil diameter
Transmitivity of stereoscope for white light
Illumination at retina in % of unaided vision
Flare as % of average brightness (luminance) of 23 x 23
(measured on area with Q = 1/M cm) of 10 cpn^
Illumination under practical conditions (subjective) . .
False images (subjective) . .
Direct Flare into the eye (subjective) . .
. mm
. cm
. mrad
Image Quality
Transfer Function approx, by a Gauss-TF : -* 2 cr of SF . . . pm
Spatial frequency at 50% contrast lines/mm
Difference in Image Quality between x and y direction
Central area of good Image Quality (% of A (point 4))
Useful focussing range of eyepiece dioptre
Refocussing needed when changing Magnification M2 -* Mj. dioptre
Good
Tolerable
Poor
> 0. 9
0. 7-0.9
< 0.7
> 15
12-15
8-12
> 25
20-25
0. 8-1.0
1.0-1. 5
0. 6-0. 8
3-4
4-6
> 6
2-3
3-4
4-6
> 60%
30-60%
< 30%
> 10%
2-10%
< 2%
< 20%
< 20
20-40
> 40
65+10
64+8
64+5
> 25
21-25
< 21
-1 - +3
+1
< 1%;1/M
1-3%
> 3%;3/M
< 10
10-20
> 20
< 1/M
1/M-3/M
> 3/M
< 10
10-20
> 20
> 90
80-90
prints
opt. axes
scope
> +10
< 1/M
1/M-3/M
> 3/M
20x23
< 20
20-200
3-4
4-5
2-3
> 50%
40-50%
25-40%
> 50%
25-50%
10-25%
< 3%
3-10%
10-20%
< 2%?
2-5% ?
5-10%
easy
moderate
hard
no
at edge
at centre
no
some
more
< 15
15-25
> 25
> 35
20-35
< 20
no
10%
10-20%
> 90%
50-90%
< 50%
- +6
+ 5
one < 5
< +0. 5
0. 5-1
> ±1
100
100% Modulation
-
Modulation
Transfer
-
Ft
incti
DÌÌ Oil
xis
-
-
1
0 1/mm
15 20 30 40
Observed Area at Magn.
Area of constant quality
