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Key
Benefits of a Micro-Machined Optically Integrated (MMOI) Sensor
- Can
survive in a harsh operating environment
- Has
high spatial and temporal response
- Can
be used to obtain multi-parameter data
The
micro-machined Fabry-Perot cavity sensor consists of two parallel
partially reflecting surfaces separated by a gap. Light is introduced
into the Fabry-Perot cavity through an optical fiber. The reflected
light following multiple reflections within the cavity is carried
back through the same fiber. This results in a periodic variation
of the reflected light intensity as a function of the cavity depth
h. The reflected light from the sensor is spectrally shifted. A ratio
of two detectors was used to detect the spectral shift from which
the pressure can be derived. |
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Figure
1. Schematic of a MMOI; Cavity diameter = 300 micron, Diaphragm thickness
= 12 micron |
Figure
2. Assembly of Optical Detection and Differential Amplification Box |
Differential
and absolute pressure sensors were fabricated and tested under static
and dynamic test conditions. The sensors provide extremely accurate,
repeatable results over the designed range of operation. Dynamic testing
results show that frequency response in the 180 KHz range was obtained.
The sensor 1) can survive in a harsh operating environment, 2) has
high spatial and temporal response, and 3) can be used to obtain multi-parameter
data. |
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