Absolute pressure gage for ultra-high vacuum measurement

Claim 1

APPARATUS FOR MEASURING VERY SMALL PRESSURE PRODUCED FORCES, COMPRISING IN COMBINATION, (1) A SENSOR DEVICE ROTATABLE ABOUT A FIXED POSITION AXIS OF ROTATION AND INCLUDING, (A) A TARGET ELEMENT UPON WHICH THE PRESSURE PRODUCED FORCE TO BE MEASURED ACTS, (B) A RADIATION RECEIVING SURFACE COUPLED TO SAID TARGET ELEMENT IN FIXED RELATION THERETO DISPOSED LATERALLY OF SAID AXIS OF ROTATION AND UPON WHICH SURFACE RADIATION IS SELECTIVELY DIRECTABLE TO PRODUCE A TORQUE TENDING TO ROTATE SAID SENSOR ABOUT SAID AXIS OF ROTATION IN A FIRST SENSE, (C) SAID TARGET ELEMENT EXTENDING LATERALLY OF SAID AXIS OF ROTATION SO THAT A NET PRESSURE PRODUCED FORCE TO BE MEASURED ACTING THEREON PRODUCES A TORQUE TENDING TO ROTATE SAID SENSOR IN A SECOND SENSE OPPOSITE TO SAID FIRST SENSE ABOUT SAID AXIS OF ROTATION, (2) MEANS FOR EFFECTING COMMUNICATION BETWEEN A PRESSURE PRODUCING SOURCE AND THE TARGET ELEMENT, (3) MEANS FOR SUSPENDING SAID SENSOR FOR ROTATION ABOUT SAID FIXED POSITION AXIS, (4) CONTROL SIGNAL GENERATING MONITOR MEANS EFFECTIVE TO DETECT ROTATION OF SAID SENSOR AND GENERATE CONTROL SIGNALS UNIQUELY CORRESPONDING TO SAID ROTATION, (5) RADIATION PROJECTING MEANS DISPOSED FOR PROJECTING RADIATION ONTO THE SAID RADIATION RECEIVING SURFACE OF SAID SENSOR, (6) CONTROL MEANS COUPLED TO SAID MONITOR MEANS AND TO SAID RADIATION PROJECTING MEANS EFFECTIVE RESPONSIVE TO THE CONTROL SIGNALS GENERATED BY SAID MONITOR MEANS TO CONTROL THE QUANTA OF RADIATION PROJECTED ONTO SAID SENSOR TO THEREBY PRODUCE A TORQUE ON SAID SENSOR EQUAL AND OPPOSITE TO THAT PRODUCED BY THE FORCE BEING MEASURED, AND (7) MEANS RESPONSIVE TO THE CONTROL SIGNALS GENERATED BY SAID MONITOR MEANS EFFECTIVE TO INDICATE THE MAGNITUDE OF THE NET PRESSURE PRODUCED FORCE TO BE MEASURED.