Optical Sensor Ambient Gas Compensation
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Solution Overview
Problem
Existing optical sensors fail to accurately measure materials in samples due to interference from ambient gases, leading to inflated measurements as they do not account for or eliminate the presence of the material of interest in the ambient environment.
Innovation Solution
The design incorporates a compensation sensor and method to measure and normalize the intensity of electromagnetic radiation at different path lengths, using dichroic splitters and partially transmissive mirrors to distinguish between absorption by the material of interest and ambient gases, allowing for the correction of measurements by subtracting additional absorbance attributed to ambient material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical sensors measure material concentration in a sample, then the measurement can detect the presence and amount of the material, but the measurement becomes inflated due to ambient gas interference
Solution Approach 1:
The optical path is segmented into two distinct paths: a sample path where monitoring radiation passes through the sample, and a reference path where reference radiation passes through a reference window. This segmentation allows the system to separately measure and compensate for ambient gas interference, resolving the contradiction between detecting material concentration and avoiding ambient interference.
Solution Approach 2:
A reference window is introduced as an intermediary element in the reference path. This reference window serves as a mediator that experiences the same ambient gas conditions as the sample window but does not contain the material of interest. By measuring through the reference window, the system can isolate and subtract ambient gas absorption from the total measurement, thereby eliminating the harmful ambient interference while maintaining the ability to detect the material in the sample.
2Measurement precision
If the optical path length is increased to improve measurement sensitivity, then the detection capability enhances, but the impact of ambient gas interference increases
Solution Approach 1:
The system continuously measures the reference radiation intensity through the reference window and uses this information as feedback to correct the sample measurement. The reference measurement provides a real-time indicator of ambient gas conditions, allowing the system to dynamically compensate for ambient absorption effects. This feedback mechanism enables the system to maintain high detection sensitivity through extended path lengths while continuously correcting for increasing ambient interference.
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 approach enables more accurate measurements by isolating and compensating for ambient gas interference, thereby improving the precision of detecting materials in samples by accounting for the difference in path lengths and relative sensitivities of primary and compensation sensors.
Implementation Method 1
The operation of many optical sensors is based upon a scientific principle known as 'absorbance' or 'attenuation' of electromagnetic radiation, such as light or infrared radiation.
Implementation Method 2
using dichroic splitters and partially transmissive mirrors to distinguish between absorption by the material of interest and ambient gases
Data Source
AI summary
An optical sensor is configured to determine an amount of at least one material in a sample without interference from any of the material of interest present in an ambient environment in which the optical sensing is effected. The optical sensor may include a compensation detector positioned a different distance apart from a source of monitoring radiation than the distance that a primary, measurement detector is positioned from the source. Alternatively, the optical sensor may include an optically transparent material that consumes space within the sensor and, thus, eliminates ambient amounts of a material of interest from at least a portion of an optical pathway through the sensor. A calibration element transmits calibration radiation to one or more detectors of an optical sensor to facilitate correction of any changes in the manner in which the one or more detectors sense radiation. Optical sensing methods are also disclosed, as are calibration methods.