Gas Measurement Module Shortened Optical Path
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional gas measurement modules for respiratory circuits face challenges in maintaining precision and accuracy due to beam expansion and ambient path length, while also requiring a compact form factor and robustness against mechanical abuse and temperature variations.
Innovation Solution
A gas measurement module with a chamber, an infrared source, a movable filter member, and a photosensitive detector, where the filter member is actuated between positions to filter electromagnetic radiation in specific wavelength bands, and the optical path is kept short to minimize ambient path length and beam expansion, using a single photosensitive detector for self-referencing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional gas measurement module uses a longer optical path to improve measurement precision, then measurement precision improves, but device length and form factor increase
Solution Approach 1:
The patent introduces a folded optical path design where the optical path is bent back on itself within the compact housing. The infrared source and detector are positioned close together, but the optical path travels through the sample gas multiple times by reflecting off mirrors or using a folded configuration, effectively increasing the measurement path length without increasing the device's external dimensions.
Solution Approach 2:
The optical components are nested within each other in a compact arrangement. The optical path is folded back through the sample gas chamber multiple times, with mirrors and optical elements positioned to create a compact nested structure that maximizes the optical path length within the smallest possible volume.
2Measurement precision
If the optical path is extended to improve measurement accuracy, then measurement accuracy improves, but beam expansion increases
Solution Approach 1:
The folded optical path design keeps the beam confined within a compact volume by reflecting it back through the same region multiple times. This prevents beam expansion from occurring over a long linear distance, as the beam repeatedly passes through the same sample gas region in a folded configuration rather than expanding over an extended linear path.
3Adaptability or versatility
If multiple photosensitive detectors are used to measure different wavelength bands, then measurement capability improves, but device complexity and power consumption increase
Solution Approach 1:
A single photosensitive detector is used in conjunction with a moving filter that dynamically changes the wavelength band being measured. The filter is positioned in the optical path and can be moved to different positions to select different wavelength bands, allowing the single detector to measure multiple gas components by time-multiplexing the wavelength selection.
Solution Approach 2:
The single photosensitive detector serves multiple functions by measuring different wavelength bands at different times. The moving filter enables the detector to universally detect various gas components (such as CO2, O2, N2O) by sequentially positioning different filter sections in the optical path, making one detector perform the work of multiple detectors.
4Volume of moving object
If the device is designed for compact form factor to facilitate installation, then ease of installation improves, but robustness against mechanical abuse decreases
Solution Approach 1:
The moving filter is designed with a robust mechanical actuation system that can withstand the vibrations and mechanical stresses of the operating environment. The filter mounting structure and actuator are engineered to be vibration-resistant, and the optical components are securely mounted to prevent damage from mechanical abuse despite the compact housing.
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 precision and accuracy of gas composition analysis while maintaining a compact and robust design, reducing the impact of beam expansion and ambient path length, and minimizing power consumption and heat generation.
Implementation Method 1
The infrared source is configured to emit infrared electromagnetic radiation along an optical path that passes through the flow path formed by the chamber
Implementation Method 2
The movable filter member includes a first filter element configured to filter electromagnetic radiation in a first wavelength band, and a second filter element configured to filter electromagnetic radiation in a second wavelength band
Implementation Method 3
The photosensitive detector is held at a fixed position along the optical path to receive infrared electromagnetic radiation that has been filtered by the filter member and has passed through the flow path formed by the chamber
Data Source
AI summary
Gas within a ventilation circuit (12) is analyzed by a spectrometer included in gas measurement module (16) that is inserted into the respiratory circuit. The gas measurement module includes an infrared source and a movable filter member comprising at least two filter elements. The optical path length of the spectrometer is reduced. This includes removing optical components configured to collimate or focus electromagnetic radiation within the spectrometer. However, path length of the spectrometer is reduced to the point that other enhancements associated with path length reduction outweigh losses to precision and/or accuracy caused by beam expansion in the spectrometer.