Optical Sensor Transmission Arm Dynamics for Sensitivity
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Solution Overview
Problem
Existing optical sensor devices face challenges in achieving a balance between size reduction and sensitivity, particularly in dynamic applications where a broad operational frequency range is required, often compromising on sensitivity and resonance frequency due to mechanical constraints.
Innovation Solution
The design incorporates a compact optical sensor device with a pivotable transmission arm that amplifies sensitivity and operational frequency range by minimizing rotational inertia, using a reference body and sensing transducer connected via a first and second transmission arm, allowing for efficient strain modification in the optical fiber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of the optical sensor device is reduced, then the device becomes more compact and easier to implement, but the sensitivity of the sensor deteriorates
Solution Approach 1:
The patent employs a pivotable transmission arm that can rotate about a pivot point, transforming the sensing transducer's linear motion into amplified motion at the optical fiber connection point. This dynamic mechanism allows a compact device to achieve high sensitivity through motion amplification rather than simply scaling up component sizes.
Solution Approach 2:
The transmission arm acts as an intermediary mechanical element between the sensing transducer and the optical fiber. It mediates the force transmission and provides mechanical advantage, allowing the small displacement of the sensing transducer to be converted into larger strain on the optical fiber, thereby maintaining sensitivity in a compact design.
2Volume of moving object
If the size of the optical sensor device is reduced, then the device becomes more compact, but the operational frequency range is limited
Solution Approach 1:
The pivotable transmission arm creates a dynamic system where the effective lever arm length can be optimized to achieve high resonance frequency. By positioning the optical fiber connection point appropriately along the transmission arm, the system achieves both compactness and extended operational frequency range through dynamic motion characteristics rather than static scaling.
3Measurement precision
If a pivotable transmission arm is used to amplify sensitivity, then the operational frequency range increases, but the device complexity increases
Solution Approach 1:
The patent integrates the transmission arm directly into the sensor housing structure, merging multiple functions into a single integrated component. This reduces device complexity by eliminating separate mounting structures and simplifying the mechanical assembly, while still maintaining the pivotable transmission arm mechanism for sensitivity amplification.
4Measurement precision
If the transmission arm length is increased to improve sensitivity, then the sensitivity increases, but the rotational inertia increases
Solution Approach 1:
The transmission arm is designed with non-uniform cross-sectional properties along its length, with the thickest section positioned at the pivot point where bending moments are highest. This local quality variation optimizes structural strength and minimizes rotational inertia by concentrating material where it is most needed for structural integrity rather than uniformly distributing mass, thereby improving sensitivity without proportionally increasing rotational inertia.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the sensor's responsiveness to high frequencies, improves accuracy in static and dynamic parameter measurement, and reduces cross-axis sensitivity, enabling a broader operational frequency range while maintaining compactness and high sensitivity.
Implementation Method 1
A typical example of an intrinsic fiber optic sensor is a Fiber Bragg Grating (FBG). An FBG comprises a fiber having a core including therein, over a certain distance, a periodic variation of the refractive index. This periodic variation forms a wavelength-specific dielectric mirror, wherein light in a specific (narrow) range around and including a certain wavelength is reflected. The wavelength reflected is determined by the periodicity of the refractive index of the core. The FBG is based on the principle that a difference in strain of the optical fiber causes the geometric periodicity of the variations to change. This results in a change of the reflected wavelength, which change can be detected
Data Source
AI summary
The invention relates to an optical sensor device comprising a reference body and at least one sensing transducer. The sensing transducer is arranged for receiving an input action, and is movably arranged relative to the reference body for moving relative to the reference body in response to the input action. The device further comprises an optical fiber and one or more transmission arms including a first transmission arm. The optical fiber comprises an intrinsic fiber optic sensor. The optical fiber is connected with a first connecting part thereof to the first transmission arm and with a second connecting part thereof to an element exterior to said first transmission arm. The first connecting part and the second connecting part are on either side of the intrinsic fiber optic sensor. For receiving the input action, a base of the first transmission arm is connected at a first part thereof with the reference body and with a second part thereof with the sensing transducer. The optical fiber is connected at a location along the first transmission arm remote from the base thereby converting the input action received by the sensing transducer into a sensing action applied to the optical fiber such as to modify strain in the optical fiber dependent on said input action.