Thermal Triangulation Surface Measurement for Reflective Materials
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Solution Overview
Problem
Existing non-contact measurement methods fail to provide accurate results for highly reflective, transparent, translucent, or highly absorbent object surfaces due to insufficient irradiance, long exposure times, and thermal diffusion, making them unsuitable for materials like glass, metal, or fiber-reinforced composites.
Innovation Solution
A method involving a radiation source that generates a time-varying temperature distribution by irradiating small, spatially confined surface elements with successive pulses, using thermal imaging cameras to capture and identify corresponding points through triangulation, allowing for high-contrast, rapid measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a radiation source irradiates a large area of the object surface, then the measurement coverage is improved, but the irradiance per unit area decreases and thermal diffusion increases
Solution Approach 1:
The patent segments the measurement process by dividing the object surface into multiple small areas that are irradiated sequentially by the radiation source. The controller coordinates the radiation source to irradiate different spatially confined surface elements in succession, allowing each area to receive high irradiance while the overall measurement covers a large surface area through the combination of multiple segmented measurements.
2Measurement precision
If the radiation source irradiates for a long exposure time, then the thermal diffusion increases, but the signal-to-noise ratio improves
Solution Approach 1:
The patent employs periodic pulsed irradiation instead of continuous irradiation. The controller activates the radiation source in periodic pulses with optimized duration, allowing each pulse to provide sufficient energy for high signal-to-noise ratio while the间歇性 (intermittent) nature of the pulses limits the total exposure time and reduces thermal diffusion. The thermal imaging camera captures images during or immediately after these periodic pulses.
3Ease of operation
If conventional projection methods are used on highly reflective or transparent surfaces, then the measurement process is simple, but the measurement accuracy deteriorates
Solution Approach 1:
The patent replaces conventional optical reflection-based measurement with thermal radiation-based measurement. Instead of relying on reflected light patterns from the projection device, the system uses a radiation source to heat the surface and a thermal imaging camera to detect thermal radiation emitted by the object. This substitution of the measurement mechanism enables accurate measurement of highly reflective, transparent, or translucent surfaces that are difficult to measure with conventional optical methods.
4Measurement precision
If the radiation source irradiates small spatially confined surface elements, then the thermal diffusion impact is reduced, but the measurement speed decreases
Solution Approach 1:
The patent implements dynamic coordination between the radiation source, controller, and thermal imaging camera. The controller dynamically adjusts the irradiation pattern and timing based on the measurement requirements, optimizing the balance between spatial confinement (for reduced thermal diffusion) and measurement speed. The system can adaptively select which surface elements to irradiate and when, allowing efficient coverage of large areas while maintaining precision through optimized dynamic control of the measurement process.
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
Enables faster and more accurate measurement of challenging surfaces by concentrating radiation on small areas, reducing thermal diffusion impact and increasing signal-to-noise ratio, suitable for transparent or translucent materials.
Implementation Method 1
the radiation source is configured such that the radiation causes a temperature increase on the object surface upon impact
Implementation Method 2
acquisition and processing of thermal images acquired with at least one thermal imaging camera
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a device (1) and a method for measuring an object surface in a contactless manner. In the method according to the invention a temporally variable temperature distribution is produced on the object surface (2) by serially applying a plurality of thermal patterns (9) to the object surface (2). Next, in each case a thermal image of the object surface (2) is captured by at least one thermal imaging camera (16, 17) at a plurality of successive recording times, so that a sequence of thermal image values is captured for each point in an image plane (18, 19) of the thermal imaging camera or each of the thermal imaging cameras (16, 17). Following this, corresponding points (20, 21) in the image planes (18, 19) of the thermal imaging cameras (16, 17) or in the image plane of the thermal imaging camera and in an image plane assigned to the radiation source (6) are identified by maximising a similarity between the sequences of thermal image values captured or simulated for potentially corresponding points. Then spatial co-ordinates of the object surface (2) are determined by triangulation on the basis of the points (20, 21) identified as corresponding. Surface elements irradiated during application of the patterns (9) are spatially delimited so that an image of each area irradiated by an individual irradiation pulse in the image plane (18, 19) of the thermal imaging camera or each of the thermal imaging cameras (16, 17) is smaller than 5% of a total area of this image plane (18, 19).