Opto-mechanical Transducer Evanescent Field Gas Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current integrated systems for photo-acoustic spectrometry face challenges in achieving precise gas concentration detection due to the squeeze film effect and limitations in increasing the reception surface of mechanical sensors without compromising system size and integration.
Innovation Solution
An opto-mechanical system that utilizes a mechanical sensor with a sensor element capable of vibrating to modify the evanescent field of an optical detector, allowing for precise detection of acoustic waves generated by gas excitation, thereby overcoming the squeeze film effect and enhancing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the reception surface of the mechanical sensor is increased to maximize mechanical detection of the acoustic wave, then the detection sensitivity is improved, but the size of the system is increased which is unfavorable for integration optimization
Solution Approach 1:
The patent replaces the capacitive detection system with an optical detection system. Instead of using a mechanical sensor with electrodes for capacitive detection, the invention uses an optical sensor to detect the vibration of the mechanical sensor through optical means, thereby eliminating the squeeze film effect and improving detection sensitivity without increasing system size.
Solution Approach 2:
The patent introduces an optical intermediary to transfer the mechanical vibration signal to the optical sensor. The optical sensor detects the vibration of the mechanical sensor through optical interaction, serving as an intermediary that converts mechanical motion into optical signals without requiring direct mechanical contact or capacitive coupling.
2Measurement precision
If capacitive detection means are used with a mechanical sensor, then the system can detect acoustic waves, but the air between the mechanical sensor and electrode creates a viscous damper (squeeze film effect) that deteriorates detection
Solution Approach 1:
The patent replaces the capacitive detection system with an optical detection system. Instead of using a mechanical sensor with electrodes for capacitive detection, the invention uses an optical sensor to detect the vibration of the mechanical sensor through optical means, thereby eliminating the squeeze film effect and improving detection sensitivity without increasing system size.
Solution Approach 2:
The patent introduces an optical intermediary to transfer the mechanical vibration signal to the optical sensor. The optical sensor detects the vibration of the mechanical sensor through optical interaction, serving as an intermediary that converts mechanical motion into optical signals without requiring direct mechanical contact or capacitive coupling.
3Volume of moving object
If the size of the system is reduced for better integration, then the reception surface of the mechanical sensor is limited, but this reduces the mechanical detection capability
Solution Approach 1:
The patent replaces the capacitive detection system with an optical detection system. Instead of using a mechanical sensor with electrodes for capacitive detection, the invention uses an optical sensor to detect the vibration of the mechanical sensor through optical means, thereby eliminating the squeeze film effect and improving detection sensitivity without increasing system size.
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 system achieves precise and sensitive detection of gas concentrations, including very low levels, while maintaining a compact design, thereby improving upon the limitations of existing photo-acoustic spectrometry systems.
Implementation Method 1
The mechanical sensor is intended to receive an acoustic wave to set the sensing element vibrating at a vibration frequency
Implementation Method 2
an optical detector capable of guiding light radiation substantially parallel to the longitudinal plane, the optical detector having an evanescent field. The vibration of the sensor element modifies the evanescent field of the optical detector
Implementation Method 3
The vibration of the sensor element modifies the evanescent field of the optical detector, allowing for precise detection of acoustic waves
Implementation Method 4
when modulated light radiation, particularly laser radiation, is emitted into a medium containing the gas to be analyzed, the species constituting the gas absorbs at least part of this radiation if it has a wavelength in the absorption range of the species, causing excitation of the molecules of the species
Implementation Method 5
The relaxation of these excited molecules can take place in several different ways, including: a. By radiative relaxation causing the emission of a photon
Implementation Method 6
b. By collision with another molecule, causing the emission of heat
Implementation Method 7
By collision with another molecule, causing the emission of heat
Implementation Method 8
The emission of heat due to a collision with another molecule causes, among other things, a phenomenon of expansion and contraction of the gas
Implementation Method 9
The emission of heat due to a collision with another molecule causes, among other things, a phenomenon of expansion and contraction of the gas, which generates an acoustic wave
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
The invention relates to an opto-mechanical system for transducing displacement with an optical phase shift, comprising a mechanical sensor including a sensing element. The sensing element has an upper face extending primarily in a plane called the longitudinal plane when the system is at rest. The mechanical sensor is designed to receive an acoustic wave to cause the sensing element to vibrate at a vibration frequency. The system further comprises an optical detector capable of guiding light radiation substantially parallel to the longitudinal plane. The optical detector has an evanescent field. The vibration of the sensing element modifies the evanescent field of the optical detector, and the sensing element moves in a direction called the transverse direction, substantially perpendicular to the longitudinal plane, when it is vibrating.