Patent ID: 7500300

Claim:
A method of manufacturing a vacuum measuring cell comprising: providing a first housing body ( 1 ) made of Al 2 O 3 ceramic or sapphire material; providing a substantially planar membrane ( 2 ) made of Al 2 O 3 ceramic or sapphire material and having a peripheral edge and first and second opposing surfaces, said first surface of said membrane facing said first housing body and said first housing body having a surface facing said membrane; providing a first edge seal ( 3 ) for joining tightly the peripheral edge of the first opposing surface of the membrane to the first housing body; creating a reference vacuum chamber ( 25 ) between the first housing body and said membrane; providing a second housing body ( 4 ) made of Al 2 O 3 ceramic or sapphire material, said second opposing surface of said membrane facing said second housing body and said second housing body having a surface facing said membrane; providing a second edge seal ( 3 ′) for joining tightly the peripheral edge of the second opposing surface of the membrane to the second housing body; creating a measurement vacuum chamber ( 26 ) between the second housing body and said membrane; providing a port ( 5 ) in the second housing body for connecting the vacuum measuring chamber to a medium to be measured; providing an optical transparent window ( 33 ) in a central area of the first housing body; providing optically reflective material ( 31 ) on the central region of the first surface of the membrane; providing a lens ( 35 ) above the optical transparent window for optically linking to the optically reflective material on the membrane; providing an optical fibre ( 37 ) outside the reference vacuum chamber and at a distance from the optical transparent window for feeding light through the lens and window and in and out onto the optically reflective material on the membrane so that the level of membrane deflection may be detected by a Fabry-Perot Interferometer.