Patent ID: 8390782
Filing Date: 2013-03-05
Classification: G03B,G03F

Abstract:
1. An apparatus, comprising: a plurality of measurement chambers having first supply ports and measurement nozzles, wherein each of the plurality of measurement chambers is configured to receive fluid via the first supply port and to vent the fluid via the measurement nozzle; a reference chamber having a second supply port, a reference nozzle, and a reference surface, wherein the reference chamber is common to the plurality of measurement chambers, and is configured to receive fluid via the second supply port and to vent the fluid via the reference nozzle; a diaphragm forming a portion of a common wall of each of the plurality of measurement chambers and the reference chamber, and separating the reference chamber from each of the plurality of measurement chambers, wherein the diaphragm is responsive to pressure applied thereto; a reference standoff surface attached to the reference chamber, and located proximately opposite from the reference nozzle; a reference frame located external to the reference chamber; a position sensor attached to the reference frame, and configured to output a signal responsive to movement of the diaphragm; and a reference position sensor attached to the reference frame, and configured to output a signal responsive to movement of the reference surface.