- TECHNICAL
DATA OF GLASS
- D-BIFOCAL
6.25, 4.25, 8.25 & 2.25 BASE
1. Source of material
- i.
PGX and PBX
-
-
A)
Crown Major
+6-6x8mm,+4-6x9mm,+8-6x11mm &
+2-6x11.5mm
-
B)
Upper Segment
35 x 14 x6mm
-
C)
Barium
35 x 23.5 x6mm
-
- All above from Corning France.
- ii.
WHITE
-
-
A)
Crown Major
+6-6x8 mm, +4-6x9mm,+8-6x11mm &
+2-6x11.5mm
-
B)
Upper Segment
35 x 14 x6mm
-
C)
Barium
35 x 23.5 x6mm
-
- White blank all sourced from Schott Germany.
-
- 2) Final
Specifications of semi-finished bifocals:
-
-
|
- Base
Redius
|
- Thickness
|
- 6.25 base
|
- 84.764
|
- 6.0mm
CT
|
- 4.25 base
|
- 125.721
|
- 7.0mm
CT
|
- 8.25 base
|
- 64.567
|
- 9.0mm
CT
|
- 2.25 base
|
- 233.482
|
- 8.0mm
CT
|
- 3) De
centration:
Distance and reading centers in mm
-
-
X= Horizontal Difference
= 5.0
-
Between 2 centres
-
Y= Detum line below center
= 4.0
-
Z= Segment center below
= 5.0
-
Datum line
-
- 4) Segment Depth in mm
:
|
|
|
1.00
|
1.25
|
1.50
|
1.75
|
2.00
|
2.25
|
2.50
|
2.75
|
3.00
|
|
|
|
|
|
|
|
|
|
|
|
|
|
BASE 6.25
|
1.56
|
1.94
|
1.18
|
1.38
|
1.56
|
1.74
|
1.41
|
1.56
|
1.70
|
|
|
|
|
|
|
|
|
|
|
|
|
|
BASE 4.25
|
0.80
|
0.96
|
1.17
|
1.36
|
0.99
|
1.27
|
1.41
|
1.55
|
1.68
|
 |
