Towards Photonic based Pascal Realization as a Primary Pressure Standard

Abstract

New techniques using refractometry have enabled gas pressure to be measured using laser interferometry. Two key techniques have been studied at NIST which include the Fixed Length Optical Cavity (FLOC) and the Variable Length Optical Cavity (VLOC). The measurement techniques are described and the traceability of these measurements through quantum mechanics that enables them to be primary standards. This technology is critical for gas pressure metrology to move away from artifact based standards (and especially mercury based) and move to quantum based methods for realization of the pascal.

A constant pressure flowmeter for extremely high vacuum

“…The former is generally > 0.2 % because the absolute pressure gauge that measures p ref is currently calibrated through an intermediate transfer standard. By calibrating directly against a pressure standard such as the ultrasonic manometer (UIM) [20] or a fixed-length-optical-cavity (FLOC) [21], we estimate that we can reduce that relative uncertainty to < 0.1 %. At that point, the dominant uncertainty will be due to longterm drifts in the absolute pressure gauge, which is typically < 0.1 % [20].…”