Machined Blanks
Any of the optical glasses currently available in strip form can be cut to customer specifications. Standard tolerances for diameter and thickness are +/- 0.10 mm. Precision tolerances can be achieved to +0.00/-0.05 upon request.
Pressings
Direct-Pressings (DP) and Reheated-Pressings (RP) are directly formed from melted glass or by reheated press process. Pressing shapes can be provided to customer specifications. Pressings are offered for most materials in the CDGM Glass Catalog.
The table below summarizes the tolerances associated with lens diameters and thicknesses:
|
Direct Pressings |
Reheated Pressings |
| Diameter (mm) |
Diameter Tolerance (mm) |
Thickness Tolerance (mm) |
Diameter Tolerance (mm) |
Thickness Tolerance (mm) |
| < 12 |
± 0.10 |
± 0.20 |
± 0.10 |
± 0.50 |
| 12 to 40 |
± 0.15 |
± 0.20 |
± 0.15 |
± 0.40 |
| 41 to 60 |
± 0.20 |
± 0.20 |
± 0.20 |
± 0.30 |
| 61 to 90 |
± 0.30 |
± 0.30 |
± 0.25 |
± 0.30 |
| 91 to 150 |
± 0.40 |
± 0.40 |
± 0.40 |
± 0.40 |
| > 150 |
± 0.50 |
± 0.50 |
± 0.50 |
± 0.50 |