Fiber Optic Dosimeter with Reference Arm for Stable Low-Dose Sensing
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Solution Overview
Problem
Existing dosimeters struggle with high precision, real-time radiation dose measurement in mixed space radiation environments, particularly at low doses and dose rates, and are sensitive to temperature and polarization fluctuations, limiting their accuracy and dynamic range.
Innovation Solution
A dosimeter design using a radiosensitive optical fiber with a reference arm and a logarithmic amplifier, combined with a depolarized or polarization-maintaining optical system, to measure differential radiation-induced attenuation, reducing polarization effects and temperature sensitivity, and enabling accurate, wide-range dose measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fiber optic dosimeter based on radiation-induced attenuation measurements is used, then sensitivity at low radiation doses is improved, but the measurement becomes dependent on temperature and dose rate, reducing measurement precision
Solution Approach 1:
The optical path is segmented into multiple sections with different radiation shielding configurations. Each segment experiences different radiation doses, allowing the system to measure attenuation across multiple dose levels simultaneously. This segmentation enables temperature and dose rate compensation by comparing measurements from shielded and unshielded segments.
Solution Approach 2:
The invention changes the radiation dose parameter by introducing variable shielding in different optical path segments. By creating controlled differences in radiation exposure between segments while maintaining identical temperature conditions, the system can separate temperature effects from radiation effects, thereby improving measurement precision while reducing dependence on temperature and dose rate variations.
2Measurement precision
If the intensity of the light source is increased to improve measurement dynamic range, then the measurement precision is improved, but the device complexity and power consumption increase
Solution Approach 1:
The optical path is divided into multiple segments that can be independently shielded. This allows the system to measure radiation doses across a wide dynamic range by adjusting which segments are shielded, eliminating the need for high-intensity light sources or complex attenuation mechanisms. The segmentation provides inherent dynamic range expansion through spatial diversity.
3Device complexity
If a dosimeter is designed for space environment with small size and low mass, then the device complexity is reduced, but the ability to include temperature compensation mechanisms is limited
Solution Approach 1:
The dosimeter uses spatial segmentation of the optical path with multiple segments at different temperatures. By measuring attenuation across segments experiencing different thermal conditions, the system achieves temperature compensation without requiring active temperature control mechanisms, maintaining small size and low mass while improving measurement precision.
Solution Approach 2:
The optical fiber segments serve multiple functions: they act as both the measurement medium for radiation-induced attenuation and as temperature sensors through their thermal response. This multi-functionality eliminates the need for separate temperature compensation devices, reducing overall device complexity while maintaining measurement precision.
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 dosimeter achieves high sensitivity and accuracy at low radiation doses, with a dynamic range from 1 Gy to 100 Gy, and is insensitive to temperature and polarization fluctuations, suitable for space and medical applications.
Implementation Method 1
a light source capable of generating a light beam
Implementation Method 2
measure, over time, the optical power loss of the light beam transmitted through the optical fiber. From this, through pre-calibration, the radiation-induced attenuation in the optical fiber is deduced
Implementation Method 3
a first photodetector arranged to record a power measurement of the light beam transmitted through the radiosensitive optical fiber, a second photodetector arranged to record a reference power measurement
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a dosimeter (100) comprising a light source (1) capable of generating a light beam (10), an optical coupler-splitter (2), a radiosensitive optical fiber (3), a first photodetector (5) arranged to record a power measurement (21) of the light beam transmitted through the radiosensitive optical fiber (3), a reference optical arm (4), a second photodetector (6) arranged to record a reference power measurement (22) of the light beam transmitted through the reference optical arm (4), and an electronic system (20) configured to extract a differential measurement of radiation-induced attenuation in the radiosensitive optical fiber (3) with respect to the reference optical arm (4). According to the invention, the light beam (10) is unpolarized or depolarized, or, respectively, the light beam (10) is polarized and the radiosensitive optical fiber (3) is a polarization-maintaining fiber.