产品指标如下：

Material                                              Pyrex glass or substitute

Dia tolerance (inch)                             +0, -0.005

Dia tolerance (mm)                              +0, -0.13

Center Thickness tolerance                    ±0.010” (±0.25 mm)

Clear Aperture                                     85% Central Diameter

Parallelism                                           3 arc min

Surface Accuracy                                1/4 wave at 633 nm

Surface Quality                                   60/40

Coating                                            Protected Gold-Chromium