Patent ID: 7010958

Claim:
A gas gauge proximity sensor for sensing a difference between a reference surface standoff and a measurement surface standoff, comprising: a junction that divides gas input into the gas gauge proximity sensor into a reference channel and a measurement channel; a first switching device coupled to the measurement channel and to a plurality of measurement branches, wherein said first switching device permits gas to flow in one measurement branch at a time and can be used to switch the flow of gas from one measurement branch to another measurement branch; a first porous flow restrictor placed along the reference channel, wherein said first porous flow restrictor evenly restricts gas flow through the reference channel; a plurality of measurement branch porous flow restrictors, placed along said plurality of measurement branches, wherein each measurement branch porous flow restrictor evenly restricts gas flow through a respective measurement branch; a reference probe at an end of the reference channel, whereby gas exits the reference channel through the reference probe and travels across a reference standoff to impinge upon a reference surface; a plurality of measurement probes, wherein a measurement probe is placed at an end of each of the measurement branches, whereby gas exits a measurement branch through a measurement probe and travels across a measurement standoff to impinge upon a measurement surface; and a second switching device coupled to a bridge channel and to the plurality of measurement branches, wherein said second switching device permits gas to flow in one measurement branch at a time and can be used to switch the flow of gas from one measurement branch to another measurement branch; and a mass flow sensor coupled between the reference channel and said second switching device far sensing the mass of gas flow therebetween.