Infrared Camera Calibration for Body Temperature
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Solution Overview
Problem
Infrared cameras used for non-contact temperature measurement, especially in medical applications, suffer from low measurement accuracy due to lack of cooling, making them unsuitable for precise body temperature determination, as they often have a standard deviation greater than 1°C, which is not acceptable in medical settings where values need to be within ±0.5°C.
Innovation Solution
A calibration device with a metal outer shell, having an emissivity similar to human skin, is used in conjunction with an infrared camera to compensate for measurement inaccuracies. The outer shell is heated to match the radiant power of the object's surface, allowing for precise temperature determination by ensuring the emissivity and thermal coupling, thereby improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an inexpensive uncooled infrared camera is used for non-contact temperature measurement, then the device cost is reduced and portability is improved, but the measurement precision deteriorates with a standard deviation greater than 1°C
Solution Approach 1:
A calibration object with known thermal properties is introduced as an intermediary between the infrared camera and the measurement environment. This calibration object reflects or emits predictable infrared radiation patterns that enable the camera to learn and compensate for its own measurement errors, thereby improving precision without requiring expensive cooled sensors
Solution Approach 2:
The system dynamically adjusts measurement parameters by comparing readings from the calibration object against known reference values. Through this parameter comparison and correction process, the system compensates for the infrared camera's inherent inaccuracies, achieving medical-grade precision (standard deviation < 0.5°C) from inexpensive equipment
2Measurement precision
If a cooled infrared camera is used to achieve high measurement precision, then the measurement precision is improved, but the device cost increases and the device complexity increases
Solution Approach 1:
Instead of using complex cooled camera systems, the patent introduces a simple calibration object as a mediator that enables precision measurement through software-based correction algorithms, avoiding the need for expensive cryogenic cooling systems and complex thermal management infrastructure
Solution Approach 2:
The patent replaces the mechanical/physical solution of cooled sensors with an algorithmic/software solution. By using processing algorithms that analyze patterns from the calibration object, the system achieves high precision measurement without the mechanical complexity of cooled infrared cameras
3Measurement precision
If the emissivity of the calibration object is made similar to human skin, then the measurement accuracy for body temperature is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The calibration object is designed with specific local properties - its emissivity is optimized for the measurement region of interest. By concentrating the emissivity optimization on the calibration surface rather than requiring the entire system to achieve perfect emissivity matching, the manufacturing complexity is reduced while maintaining measurement accuracy
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 setup enables quick, reliable, and accurate non-contact temperature measurement of body temperature, reducing measurement inaccuracies and making the system cost-effective by relying on the precision of the temperature sensor rather than the infrared camera's accuracy.
Implementation Method 1
an infrared camera (10), in whose focus (11) an object (100) and an outer shell (31) of a calibration device (30) are arranged, with the outer shell (31) having an external emissivity similar to that of the object (100)
Implementation Method 2
the outer shell (31) having an external emissivity similar to that of the object (100)... allowing for precise temperature determination by ensuring the emissivity and thermal coupling
Data Source
Figure 1
AI summary
The invention relates to a measuring device (1) for contactless determination of a temperature (T) of an object (100), for example a person, comprising an infrared camera (10) having a focus (11), wherein a calibration device (30) is connected by means of a data link to the infrared camera (10), wherein the calibration device (30) has an outer shell (31) having an external emissivity similar to the object (100), wherein a temperature sensor (34) is arranged in the outer shell (31). The invention further relates to use thereof, and to methods, in particular for operating the measuring device.