Optomechanical pressure measurement system and method using the vibrational modes of a membrane

US11287334B1 · kind B1 · utility

Assignees

• UNIVERSITY OF MARYLAND, COLLEGE PARK · US
• Government of the USA, as represented by the Secretary of Commerce, National Institute of Standards and Technology · US

Inventors

• Stephen Eckel · Chapel Hill, US
• James Anthony Fedchak · Washington, US
• Thomas G. Purdy · Orrville, US
• Robinjeet Singh · Gaithersburg, US

Key dates

• Filing date: Jun 19, 2019
• Grant date: Mar 29, 2022
• Expiry date: Nov 26, 2039

Classification

• Technology area (CPC G): Physics
• CPC primary: G01L27/005
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

An optomechanical pressure-measurement system measures pressure in the range of 10−6 Pa-10−2 Pa by measuring various properties of a vibrational mode of an ultra-thin membrane member. With independent measurements of the thickness and density of the membrane, in addition to the measured vibration mode properties, the system can operate as a primary pressure sensor. The membrane member is mounted on a vibration-isolated mount and is excited by a drive force. A laser beam impinges on the excited membrane, and an optical phase detector detects the amplitude of the oscillations, as well as parameters of the laser beam affected by the membrane vibration. In one embodiment, a mechanical damping is computed based on the amplitude or frequency shift (depending on the pressure range), and the pressure based on the ring-down time of the membrane vibration mode.