8.4 Saw cut Centre-less Ground Cylindrical Blanks

These blanks are cut from a precisely ground rod formed on a centre-less grinding machine. This process is very useful for making lenses that:

• Are small in diameter but quite thick
• Are small in diameter with shallow radii
• Are such that the precise blank dimension can eliminate lens centreing operations
• Can utilize precision spot blocks

Diameter range of these blanks is 3 mm to 20 mm. The dimensional tolerances are given in table 15.

Centre-less ground blanks can be supplied in any glass type.

8.5 Mouldings

Pressing large blanks over 300 mm in diameter or of an excessive thickness is difficult. Such large blanks are gravity moulded. Blanks made by this method are generally supplied plano-plano. However, we can also produce large plano-convex or plano-concave mouldings.

8.6 High Homogeneity Glass

OHARA utilizes our leading edge technology to provide high homogeneity blanks in various glass types. Interferograms indicating the homogeneity of these blanks are typically provided with each shipment.