How do fiber optic pressure sensors work?

In summary, there are various types of pressure sensors, but the most popular ones are based on diaphragm design. They use a regular fiber with a diaphragm on the end to sense pressure changes. However, other types such as Fabry-Perot etalon or Mach-Zehnder interferometers are also commonly used. These sensors work by detecting changes in interference patterns caused by pressure changes. Fabry-Perot devices are more common in industry, while Mach-Zehnder devices are smaller in size.
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hxtasy
112
1
In a nutshell? i cannot seem to find a lot of information online about these. Could someone please help?


thanks!
 
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  • #2
It depends on the type of sensor. The most popular is probably the diaphragm design. They are basically just a regular fiber with a diaphragm on the end that is normal to the fiber. Light is sent to the end of a fiber via a fiber coupler and received by a photodiode/phototransistor. As the pressure increases, the diaphragm deforms and causes more light from the fiber to deflect thereby lowering the return intensity/optical path.

Here's a white paper about some commercial ones pressure sensors:
http://www.fiso.com/modules/AxialRealisation/img_repository/files/documents/2007/Miniature%20Fiber%20Optic%20Pressure%20Sensor%20for%20Medical%20Applications%20IABP%20therapy_2005%20OFS-17.pdf
 
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  • #3
Topher925 said:
It depends on the type of sensor. The most popular is probably the diaphragm design. They are basically just a regular fiber with a diaphragm on the end that is normal to the fiber. Light is sent to the end of a fiber via a fiber coupler and received by a photodiode/phototransistor. As the pressure increases, the diaphragm deforms and causes more light from the fiber to deflect thereby lowering the return intensity/optical path.

Old post, but updating in case anyone encounters this.

The previous post seems to describe a sensor based on physical dimming due to a diaphragm reducing light reflected back into the fiber. There may be a sensor like that, but the more common types are based on Fabry-Perot etalon or Mach-Zehnder interferometers, and interference patterns. There is an element in these that is sometimes called a "diaphragm", but it is related to changing the distance light travels on a leg of the interferometer. Pressure changes vary the path length, which cause the light/dark bands of the interference pattern to shift. A photo sensor detects the number of light/dark changes moving past it, and the count is then translated into a pressure.

I remember an optics lab experiment where I used a two leg fiber based Mach-Zehnder interferometer. One fiber leg of the device was exposed to the pressure to be measured, and the other shielded. The pressure changes on the exposed fiber cause internal reflection differences resulting in path differences. I think the F-P devices are more common in industry than the M-Z based, especially where small size is important.
 
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1. How do fiber optic pressure sensors detect pressure?

Fiber optic pressure sensors work by using a fiber optic cable that is sensitive to changes in pressure. The cable is designed to deform when pressure is applied, which changes the way light travels through it. This change in light can be measured and converted into a pressure reading.

2. How accurate are fiber optic pressure sensors?

Fiber optic pressure sensors are highly accurate, with a resolution as low as 0.01% of full scale. They also have a wide measurement range and can withstand high pressures without losing accuracy.

3. What are the advantages of using fiber optic pressure sensors?

Fiber optic pressure sensors have several advantages over traditional pressure sensors. They are immune to electromagnetic interference, have a fast response time, and can be used in harsh environments such as high temperatures and corrosive chemicals.

4. How do fiber optic pressure sensors compare to other types of pressure sensors?

Fiber optic pressure sensors have several advantages over other types of pressure sensors, such as strain gauge and piezoelectric sensors. They have a smaller size, higher accuracy, and are not affected by electrical interference. They also have a wider measurement range and can be used in more extreme environments.

5. Can fiber optic pressure sensors be used in medical applications?

Yes, fiber optic pressure sensors are commonly used in medical applications such as blood pressure monitoring, catheter pressure measurement, and respiratory monitoring. They are biocompatible, sterilizable, and can provide accurate and real-time pressure readings.

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