|
TIPS NO |
220 |
|
Revision |
B |
|
Date: |
Apr 2005 |
Signet Standard Resin
Single vision, Flat-top Bifocal and Trifocal
Lens Product Specifications.
Purpose:
The following information is
intended to provide basic processing information for the Signet Single Vision, Flat-top 28
Bifocal, Flat-top 35 Bifocal, 7x28 Trifocal Lenses. (Based on
a 1.530 Tooling index.)
Summary of Revisions: The Single Vision 75mm diameter lenses were added.
|
Characteristics |
Signet Lens |
|
Refractive
Index |
1.499 |
|
Dispersion
Value (Abbe) |
58.0 |
|
Density |
1.32 |
|
Visible
Light |
92% |
|
Rear
Surface Coating |
Not Needed |
|
UV
Transmission Cutoff |
355 nm |
|
Chemical
Resistance |
Excellent |
|
Machinability |
Excellent |
Blank
Size: 70mm and 75mm diameter
Base Curves:
0.50*, 2.00, 4.25, 5.25†, 6.25, 7.25*, 8.25, 9.25*, 10.25*
* Available
in 70mm Single Vision only
†Available in 70mm Single Vision and
FT28 only
SV
75, FT28, FT35 & 7x28: -7.25 to +7.00
Add Powers: FT28: 0.75 to 3.50 in 0.25 Diopter steps
FT35:
1.00 to 3.00 in 0.25 Diopter steps
7x28:
1.50 to 3.00 in 0.25 Diopter steps
Flat-Top Inset: Bifocals: 5mm
in, 5mm down
Trifocals: 5mm
in, 1mm down
Signet Lenses Characteristics & Dimensions
Single
Vision Lenses
70mm
|
Nominal Curve |
True Curve |
Radius mm |
SAG at 50mm |
Nominal Concave |
Edge Thickness |
Center Thickness |
|
0.50 |
0.42 |
1261.905 |
0.25 |
6.75 |
17.0 |
9.4 |
|
2.00 |
2.03 |
261.084 |
1.20 |
6.75 |
14.5 |
8.8 |
|
4.25 |
4.27 |
124.122 |
2.54 |
6.75 |
11.0 |
8.0 |
|
5.25 |
5.17 |
102.515 |
3.10 |
6.75 |
11.0 |
9.1 |
|
6.25 |
6.17 |
85.900 |
3.72 |
6.75 |
11.0 |
10.3 |
|
7.25 |
7.17 |
73.919 |
4.36 |
6.75 |
7.0 |
7.0 |
|
8.25 |
8.17 |
64.871 |
5.01 |
6.75 |
7.5 |
10.3 |
|
9.25 |
9.17 |
57.797 |
5.69 |
6.75 |
6.8 |
10.0 |
|
10.25 |
10.25 |
51.707 |
6.45 |
6.75 |
7.5 |
13.7 |
75mm
|
Nominal Curve |
True Curve |
Radius mm |
SAG at 50mm |
Nominal Concave |
Edge Thickness |
Center Thickness |
|
2.00 |
2.03 |
261.084 |
1.20 |
6.75 |
16.0 |
10.0 |
|
4.25 |
4.27 |
124.122 |
2.54 |
6.75 |
12.0 |
9.1 |
|
6.25 |
6.17 |
85.900 |
3.72 |
6.75 |
9.0 |
8.6 |
|
8.25 |
8.17 |
64.871 |
5.01 |
6.75 |
11.5 |
14.0 |
FLAT-TOP 28
Bifocals
|
Nominal Curve |
True Curve |
Radius mm |
SAG at 50mm |
Nominal Concave |
Edge Thickness |
Center Thickness |
|
2.00 |
2.03 |
261.084 |
1.20 |
6.75 |
14.5 |
8.8 |
|
4.25 |
4.27 |
124.122 |
2.54 |
6.75 |
11.0 |
8.0 |
|
5.25 |
5.17 |
102.515 |
3.10 |
6.75 |
11.0 |
9.1 |
|
6.25 |
6.17 |
85.900 |
3.72 |
6.75 |
11.0 |
10.3 |
|
8.25 |
8.17 |
64.871 |
5.01 |
6.75 |
7.5 |
10.3 |
FLAT-TOP 35
& 7x28 Trifocals
|
Nominal Curve |
True Curve |
Radius mm |
SAG at 50mm |
Nominal Concave |
Edge Thickness |
Center Thickness |
|
2.00 |
2.03 |
261.084 |
1.20 |
6.75 |
14.5 |
8.0 |
|
4.25 |
4.11 |
128.954 |
2.45 |
6.75 |
11.0 |
8.0 |
|
6.25 |
6.22 |
85.209 |
3.75 |
6.75 |
11.0 |
10.3 |
|
8.25 |
8.38 |
63.246 |
5.15 |
6.75 |
7.5 |
10.3 |
General: Standard pads
and polish materials used for surfacing CR-39® lenses can be applied to
the Signet
Lenses. If you have questions, please
contact Technical Services at 800-759-0075.
Computer Calculation of Rx: The easiest, most efficient method to calculate and
process values for an Rx is to use an existing computer software package that
contains Signet Lens design data. If
your software does not
include this data, our Technical Services group will be happy to provide the
necessary specifications. Please forward
us the contact name and phone number of your software vendor. If you need a software program for processing
lenses, Signet Armorlite has developed a computer program to calculate
surfacing data. This program is
available through Signet Armorlite's Technical Services Department.
AR Coating: Because lens impact resistance is reduced by AR coatings, we
recommend conducting impact tests for lenses AR coated and sold by your
lab. It may be necessary to increase
the minimum center thickness in order to meet impact resistance
requirements. Please call Technical
Services at (800) 759-0075 for additional information about coatings and impact
resistance.
Impact Resistance: As a component, lenses of this design have
been shown by testing to be capable of being processed to meet applicable
impact resistance of FDA Regulations 21 CFR 801.410 and ANSI Z80.1. Conformance
to this standard is the responsibility of all subsequent processors. Impact
resistant lenses are not unbreakable. Obviously damaged lenses should be
replaced immediately.
CR-39
is a registered trademark of PPG
Signet Standard
Resin SV, FT & Tri Base Curve
Selection Chart
