Optical Sensor Resin Fill for Stray Light Reduction
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Solution Overview
Problem
Existing optical force sensors are prone to inaccuracies due to foreign matter entering the optical path and suffer from signal-to-noise ratio degradation caused by stray light, especially at interfaces between different refractive indices.
Innovation Solution
The optical sensor design includes a base portion, an action portion, and a detection unit with a reflecting member, where the space between the detection unit and the reflecting member is filled with a light transmissive material, such as resin, to prevent foreign matter entry and minimize stray light, ensuring accurate force and acceleration detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the optical path is left open for access, then ease of operation is improved, but foreign matter enters the optical path degrading measurement precision
Solution Approach 1:
A transparent cover glass is used to seal the optical path, preventing foreign matter entry while maintaining optical accessibility. The cover glass forms a protected enclosure that allows light to pass through while blocking contaminants from reaching the optical components.
Solution Approach 2:
The cover glass acts as an intermediary element between the external environment and the optical path. It mediates the interaction by allowing light transmission while providing a physical barrier against foreign matter, thus protecting the optical components without compromising the detection function.
2Ease of manufacture
If interfaces between transparent medium and air are present, then ease of manufacture is improved, but stray light is generated degrading signal-to-noise ratio
Solution Approach 1:
A resin layer is introduced as an intermediary material between the cover glass and the action portion. This resin layer has a refractive index that reduces the difference between adjacent media, minimizing reflection and stray light generation at interfaces while maintaining structural integrity.
Solution Approach 2:
The refractive index parameter is optimized by selecting a resin material with appropriate optical properties. By changing the refractive index parameter of the intermediate layer, the patent reduces optical interference and stray light effects, thereby improving the signal-to-noise ratio without complicating the manufacturing process.
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 configuration enhances the accuracy and reliability of force and acceleration detection by preventing foreign matter entry and reducing stray light interference, resulting in a high-precision optical sensor.
Implementation Method 1
a space between the detection unit and the reflecting member is filled with a light transmissive material
Implementation Method 2
a force and/or acceleration is detected due to the light receiving element detecting light emitted from the light source and reflected by the reflecting member
Data Source
AI summary
There is provided an optical sensor that includes a base portion, an action portion, a reflecting member disposed at one of the base portion and the action portion, and a detection unit including a light source and a light receiving element disposed at the other one of the base portion and the action portion. In the optical sensor, a space between the detection unit and the reflecting member is filled with a light transmissive material, and a force and/or acceleration is detected due to the light receiving element detecting light emitted from the light source and reflected by the reflecting member.