Quartz Plate Deflection Under Vacuum

Natural Quartz components, especially large ones of optical quality are costly. Given the diameter and the load sub-micron deflection is probably not a realistic goal. You should be able to use the through hole to load the component while it is finish lapped so that the surfaces are flat and parallel under load.

Since the deflection will be dependent on complex integrals of the pressure load and distance from the mount I would suggest mounting a finished optical flat of approximately 25 mm thickness in the housing and use optical means to measure the actual deflection. Then create two jigs that will impose the same amount of deflection on the part to be finished.

Mr. Gee

PS. Vector Optical would be a qualified vendor for this type work in the US.

A similar thing came up within a discussion a while ago & I recall measuring the quartz viewports on our vacuum rigs. If I remember correctly they were deflecting 0.1mm in the centre at 1x10-9mbar for a 150CF (6") viewport similar to these.

I don't think that the difference between this pressure and the one you are considering would make any difference to the deflection but having a 30mm solid stainless centre would reduce the deflection.