Minimizing Specular Reflections in a Sagnac based Fiber Gyro

In summary, the conversation discusses the speaker's project to build an airspeed flowmeter using a design based on a signac fiber optic-based gyro. The speaker has encountered a problem with specular backreflections from the fiber optic components causing interference with the weak signal. The speaker has researched and concluded that the phase modulation used by a previous group who accomplished this task may be isolating the phase-shifted signal from the reflections. The speaker is seeking advice on how to eliminate the backreflections and is hesitant to misalign the system in order to reduce them. They also ask for recommendations for resources on the topic.
  • #1
Diyon
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My project is to build an airspeed flowmeter using the design of a signac fiber optic based gyro. There is a group that has already accomplished this task (http://www.ncbi.nlm.nih.gov/pubmed/18301479), however they used a commercial fiber gyroscope whereas I am trying to build the entire setup myself.

The problem I'm encountering is the specular backreflections off my fiber optic components are washing out my inherently extremely weak signal. After a lot of reading, I have come to the conclusion that it must be their phase modulation that is somehow isolating the phase shifted signal through the DC noise of the reflections. All the other components (short coherance length source+Phase Shift) are to deal with separate problems (Rayleigh Scattering and Birefringence of the fiber).

Can anyone explain why they are able to sense such a small signal, or how they are able to eliminate the reflections off their fiber components? I found the most ideal case would be -70db of backreflection after using 8 degree cut fiber and misaligning it, both of which I am hesitant to do since it would misalign my system and my signal i calculated is -60-80db compared to my constructive signal.
 
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  • #2
Bump, if anyone can point me in the right direction of a good resource that would be helpful as well.
 

1. What is a Sagnac based Fiber Gyro?

A Sagnac based Fiber Gyro is a type of rotation sensor that uses the Sagnac effect, which is the interference of two counter-propagating beams of light in a fiber optic loop, to detect angular rotation. It is commonly used in navigation systems and other applications where precise measurement of rotation is needed.

2. Why is it important to minimize specular reflections in a Sagnac based Fiber Gyro?

Specular reflections, which are reflections of light at a single angle, can cause errors in the measurement of rotation in a Sagnac based Fiber Gyro. These errors can accumulate and affect the accuracy of the gyro, making it crucial to minimize these reflections for precise measurements.

3. How can specular reflections be minimized in a Sagnac based Fiber Gyro?

There are several ways to minimize specular reflections in a Sagnac based Fiber Gyro. These include using polarizing optics, using angled fibers, and using anti-reflective coatings on the surfaces of the fiber optic components. Careful design and alignment of the gyro can also help reduce the occurrence of specular reflections.

4. What are the potential consequences of not minimizing specular reflections in a Sagnac based Fiber Gyro?

If specular reflections are not minimized, the accuracy and stability of the Sagnac based Fiber Gyro can be compromised. This can lead to errors in measurement and potentially affect the performance of the overall system in which the gyro is being used.

5. Are there any other factors besides minimizing specular reflections that can improve the performance of a Sagnac based Fiber Gyro?

Yes, there are other factors that can improve the performance of a Sagnac based Fiber Gyro. These include temperature control, proper calibration, and using high-quality components. Additionally, regular maintenance and cleaning of the gyro can also help maintain its accuracy and stability over time.

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