Compact Gas Concentration Sensor Using Single-Window Optical Path
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Solution Overview
Problem
Concentration measuring devices for gases in semiconductor manufacturing are bulky due to separate optical fibers for light entrance and exit, requiring significant space and complicating maintenance.
Innovation Solution
A compact concentration measuring device design featuring a measuring cell with a translucent window, a reflective member, and an optical device that guides light using a light guide member and beam splitter, allowing light to enter and exit through the same window, reducing the device's size and facilitating maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate optical fibers are mounted one at either end of the measuring cell for light entrance and detection, then the concentration measurement function is achieved, but the overall size of the device increases
Solution Approach 1:
The patent merges the light entrance and light detection functions into a single optical fiber. The optical fiber is configured to enter the measuring cell at one location, and both the light source and light detector are positioned to interact with the fluid through this single fiber entry point, eliminating the need for separate optical fibers at both ends of the measuring cell.
Solution Approach 2:
The single optical fiber serves multiple functions: it acts as both the light entrance path and the light detection path. By making the optical fiber multi-functional, the device achieves concentration measurement capability while reducing the number of components and overall device size.
2Reliability
If separate optical fibers are mounted one at either end of the measuring cell, then light transmission is achieved, but the device complexity increases
Solution Approach 1:
The patent combines the light transmission and light detection pathways into a single optical fiber connection. This merging reduces the number of optical fiber connections from two (one at each end) to one, thereby simplifying the installation and reducing device complexity while maintaining reliable light transmission for measurement.
3Reliability
If optical fibers are bent with a certain radius of curvature to prevent breakage, then reliability is improved, but the space required for installation increases
Solution Approach 1:
By merging the light entrance and detection functions into a single optical fiber entry point, the patent reduces the number of optical fiber connections required. This single connection requires less installation space compared to two separate connections, while still allowing the optical fiber to be routed with adequate bend radius for reliability.
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
The design enables downsizing and ease of maintenance while maintaining accurate concentration measurements by using a reflective member to reflect light through the same window, reducing the need for separate optical paths and space allocation.
Implementation Method 1
a reflective member that reflects the light that propagates through the measuring cell, and causes the reflected light to exit from the measuring cell through the window
Implementation Method 2
an optical device that guides the light emitted from the light source to the window of the measuring cell, and guides the light exiting from the window of the measuring cell to the light detector
Implementation Method 3
a light source that emits light that enters the measuring cell through the window
Implementation Method 4
a light detector that detects light exiting from the window of the measuring cell
Data Source
AI summary
A concentration measuring device includes a measuring cell having a flow passage and a translucent window, a light source for emitting light to the measuring cell through the window, a reflective member for reflecting light propagating through the measuring cell to the window, a light detector for detecting the light exiting from the window, a calculation part for calculating the concentration of the fluid on the basis of a detection signal from the light detector, and an optical device for guiding the light from the light source to the window and guiding the light from the window to the light detector.