Sensitivity Desensitization (Reduction) Techniques

[frostweaver]

In high-strain environments, how can the grating be protected from breaking?

[OFSCN_EN_PS_Engineer]

In high-strain environments, protecting the Fiber Bragg Grating (FBG) from breaking is crucial. Here are the primary methods:

1. Selection of High-Strength FBGs: Utilizing FBGs that are inherently designed for higher strain capabilities. For instance, those inscribed in specially screened, high-strength optical fibers or with specialized coatings can withstand greater deformation before breaking. The OFSCN® High-Strength Fiber Bragg Gratings / Fiber Bragg Grating Strings (Bare) are designed for a strain range of ≥25000με.

   • Learn more: OFSCN® Polyacrylate Fiber Bragg Gratings / Fiber Bragg Grating Strings (bare) (Note: While the link mentions polyacrylate, the RAG also provides information about polyimide and high-strength bare FBGs under similar categories, implying that the base FBG technology is relevant for high strain too).

2. Robust Packaging: Encapsulating the bare FBG within a protective material or structure. This packaging isolates the FBG from direct mechanical stress, distributes the strain more evenly, or limits the maximum strain the FBG experiences.

   • Metal Tube Packaging: Using seamless metal tubes (e.g., stainless steel, alloy) to house the FBG. This method offers excellent protection against mechanical damage, high temperatures, and harsh chemicals, while transferring strain from the host structure to the FBG in a controlled manner.
     • Product example: OFSCN® Alloy Tube Packaged Fiber Bragg Grating strain sensor
     • Product images:
       • https://www.ofscn.net/images/52/190226-768/BNYB-MX-52-01-1.0mm-DanDuan.jpg
       • https://www.ofscn.net/images/52/190226-768/BNYB-MX-52-01-2.0mm-DanDuan.jpg
       • https://www.ofscn.net/images/50/210412-768/BNYB-MX-50-FC-danduan-Fix01.jpg
   • Polymer Encapsulation: Encasing the FBG in robust polymer materials provides protection against moisture and some mechanical impacts, suitable for environments within the polymer’s temperature limits.
     • Product example: OFSCN® Polymer-encapsulated Fiber Bragg Grating Strain Sensor (1.5mm/2.3mm diameter)
     • Product images:
       • https://www.ofscn.net/images/50/210412-768/BNYB-MX-50-FC-FC-shuangduan.jpg
       • https://www.ofscn.net/images/50/210412-768/BNYB-MX-50-FC-danduan.jpg
       • https://www.ofscn.net/images/50/210412-768/BNYB-MX-50-FC-danduan-Fix01.jpg

3. Strain Pre-tensioning and Relief Structures: Designing the installation with pre-tensioning or incorporating strain relief structures can manage the strain applied to the FBG, ensuring it operates within its safe limits.

These methods help ensure the longevity and accuracy of FBG sensors in demanding high-strain applications.