Development of a sapphire optical pressure sensor for high-temperature applications

David A. Mills; Dylan Alexander; Ghatu Subhash; Mark Sheplak

doi:10.1117/12.2050598

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5 June 2014 Development of a sapphire optical pressure sensor for high-temperature applications

David A. Mills, Dylan Alexander, Ghatu Subhash, Mark Sheplak

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Proceedings Volume 9113, Sensors for Extreme Harsh Environments; 91130H (2014) https://doi.org/10.1117/12.2050598
Event: SPIE Sensing Technology + Applications, 2014, Baltimore, Maryland, United States

Abstract

This paper presents the fabrication, packaging, and characterization of a sapphire optical pressure sensor for hightemperature applications. Currently available instrumentation poses significant limitations on the ability to achieve realtime, continuous measurements in high-temperature environments such as those encountered in industrial gas turbines and high-speed aircraft. The fiber-optic lever design utilizes the deflection of a circular platinum-coated sapphire diaphragm to modulate the light reflected back to a single send/receive sapphire optical fiber. The 7 mm diameter, 50 μm thick diaphragm is attached using a novel thermocompression bonding process based on spark plasma sintering technology. Bonds using platinum as an intermediate layer are achieved at a temperature of 1200°C with a hold time of 5 min. Initial characterization of the bond interface using a simple tensile test indicates a bond strength in excess of 12 MPa. Analysis of the buckled diaphragm after bonding is also presented. The packaged sensor enables continuous operation up to 900°C. Room-temperature characterization reveals a first resonance of 18.2 kHz, a flat-band sensitivity of -130 dB re 1 V/Pa (0.32 μV/Pa) from 4-20 kHz, a minimum detectable pressure of 3.8 Pa, and a linear response up to 169 dB at 1.9 kHz.

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David A. Mills, Dylan Alexander, Ghatu Subhash, and Mark Sheplak "Development of a sapphire optical pressure sensor for high-temperature applications", Proc. SPIE 9113, Sensors for Extreme Harsh Environments, 91130H (5 June 2014); https://doi.org/10.1117/12.2050598

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