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 Silver