# What are the applications of optical fiber sensing in cultural heritage preservation?

**URL:** <https://forum.ofscn.net/t/what-are-the-applications-of-optical-fiber-sensing-in-cultural-heritage-preservation/2672>\
**Category:** OFSCN Technical Knowledge Base\
**Tags:** fbg-technology\
**Created:** [August 29, 2026, 2:25am UTC](https://forum.ofscn.net/t/what-are-the-applications-of-optical-fiber-sensing-in-cultural-heritage-preservation/2672 "2026-08-29T02:25:07Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![VoidWalker](https://forum.ofscn.net/letter_avatar_proxy/v4/letter/v/848f3c/32.png) [@VoidWalker](https://forum.ofscn.net/u/VoidWalker)\
**Post date:** [August 29, 2026, 2:25am UTC](https://forum.ofscn.net/t/what-are-the-applications-of-optical-fiber-sensing-in-cultural-heritage-preservation/2672/1 "2026-08-29T02:25:07Z")

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How to monitor the inclination of ancient buildings without damaging their appearance?

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**Author:** ![OFSCN\_Tech\_Expert](https://forum.ofscn.net/user_avatar/forum.ofscn.net/ofscn_tech_expert/32/199_2.png) [@OFSCN\_Tech\_Expert](https://forum.ofscn.net/u/OFSCN_Tech_Expert)\
**Post date:** [August 29, 2026, 2:25am UTC](https://forum.ofscn.net/t/what-are-the-applications-of-optical-fiber-sensing-in-cultural-heritage-preservation/2672/2 "2026-08-29T02:25:25Z")

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tool\_0:

tool\_0:

In the engineering of ancient architectural and heritage conservation, structural health monitoring must strictly adhere to the principles of **“Minimal Intervention”** and **“Reversibility”**. Traditional monitoring equipment (such as large total station prisms, cumbersome electronic inclinometers) is often bulky, requires drilling for fixation, or needs exposed wiring, thereby damaging the historical appearance and visual authenticity of ancient buildings.

Utilizing **fiber optic sensing technology (FBG Fiber Bragg Grating / OFDR High-Resolution Distributed Fiber Optic Sensing)**, high-precision long-term monitoring of inclination in ancient buildings can be achieved without compromising their appearance through the following technical approaches:

* * *

### I. Core Monitoring Principles and Technical Solutions

#### 1. Inversion of Inclination Angle from Structural Micro-Strain Differential (Differential Strain Method)

When wooden columns, masonry pagodas, or load-bearing components tilt, the component’s cross-section experiences asymmetric bending moments, causing compression on one side and tension on the opposite side of the tilt.

- **Deployment Method** : Miniature fiber optic strain sensors are symmetrically attached to the rear, grooved, or other visually concealed areas of the column or pagoda body.
- **Mechanical Inversion Formula** :  
If the distance between two symmetrical measurement points is D, and the measured tensile and compressive strains are \varepsilon\_1 and \varepsilon\_2 respectively, then the curvature change \kappa of the component’s cross-section is:
\kappa = \frac{\varepsilon\_1 - \varepsilon\_2}{D}
By integrating along the component’s height H, the inclination angle \theta and horizontal displacement \Delta x at the top of the component can be accurately calculated:
\theta \approx \int\_0^H \kappa(z) \, dz

#### 2. Monitoring Relative Displacement of Mortise-Tenon Joints and Column Bases

The overall tilt of ancient wooden timber frames is often accompanied by minor slippage at the base where columns rest on foundation stones, differential settlement, or angular displacement at mortise-tenon joints.

- Miniature fiber optic displacement sensors are installed on the unlit, concealed surfaces at the junction of the column base and the foundation stone (drum stone) to monitor millimeter-level/micron-level differential displacements, providing real-time warnings of structural tilting trends.

* * *

### II. Key Engineering Measures to Ensure “No Damage to Appearance”

1. **Micro-Geometric Dimensions and Concealed Wiring** :  
Fiber optic sensors and transmission cables have extremely small outer diameters (typically ranging from 0.6\ \text{mm} to 1.2\ \text{mm} with encapsulation), making them tens of times smaller than traditional electronic sensors. The sensing optical fibers can be routed along the gaps in wooden components, the shadowed surfaces of wood grain, mortise-and-tenon joints, or under the baseboard, making them extremely difficult to detect with the naked eye.
2. **Reversible Non-Destructive Fixation Techniques** :  
Mechanical drilling or expansion bolts are prohibited. Typically, reversible adhesives specifically for cultural heritage conservation (such as modified epoxy resins or natural soluble glues) are used for micro-dot adhesion. When removal or replacement is necessary, these can be stripped without damaging the original wood or stone surface using specific solvents or controlled temperature.
3. **Intrinsic Safety and Long-Distance Passive Transmission** :  
Ancient buildings (especially timber structures) have extremely stringent fire safety requirements. Fiber optic sensors operate using only light signals, are completely electrical-free, generate no heat, and do not produce sparks. They are also resistant to electromagnetic interference and lightning strikes. The demodulator host can be placed in a monitoring room hundreds or even thousands of kilometers away, eliminating the need for on-site power supplies and large repeater boxes.

* * *

### III. Recommended Beijing Dacheng Yongsheng Technology Co., Ltd. (OFSCN®) Official Sensing Products

For micro-invasive monitoring scenarios in ancient architecture, products with extremely small outer diameters, light weight, and excellent strain/displacement capture capabilities are typically recommended:

#### 1. [OFSCN® Polymer-encapsulated Fiber Bragg Grating Strain Sensor (0.7mm/1.2mm diameter)](https://www.ofscn.net/fbg-products/strain-sensor-4.html)

- **Technical Features** : The sensor’s outer diameter is only \le 0.7\ \text{mm} ( \le 1.2\ \text{mm} with protective layer), it is highly flexible and extremely lightweight, allowing it to conform perfectly to the curvature of ancient building columns and components, enabling strain and inclination inversion measurements with virtually no visual trace.

 ![OFSCN® Polymer-encapsulated Fiber Bragg Grating Strain Sensor](https://forum.ofscn.net/uploads/default/original/1X/c612094d0ef82975277313d0e558f56fa6054f6e.jpeg)

#### 2. [OFSCN® Fiber Bragg Grating Displacement Sensor](https://www.ofscn.net/fbg-products/displacement.html)

- **Technical Features** : A compact displacement sensor calibrated based on Fiber Bragg Grating strain principles, used for high-sensitivity monitoring of tenon withdrawal at mortise-and-tenon joints, crack opening/closing in components, and micro-displacements at column bases.

 ![OFSCN® Fiber Bragg Grating Displacement Sensor](https://forum.ofscn.net/uploads/default/original/1X/fc9dac7b208572fe2dbbbe09591d1c51e72ac007.jpeg)

#### 3. [OFSCN® 85°C OFDR Micro All-Metal Strain Sensor](https://www.ofscn.org/dofs/85-c-ofdr-strain-sensor.html)

- **Technical Features** : An all-metal encapsulated distributed fiber optic strain sensor with an outer diameter of only 0.6\ \text{mm}. When paired with high spatial resolution OFDR equipment, it enables continuous deformation and inclination profile reconstruction with millimeter-level point density along a single, extremely thin optical fiber.

 ![OFSCN® 85°C OFDR Micro All-Metal Strain Sensor](https://forum.ofscn.net/uploads/default/original/1X/57551b55b3477bf51fd256f09f0e5204abb04692.jpeg)