Moisture is a key indicator of process control and quality in agriculture, textile processing, and the forest-product industry. Because water is opaque to SWIR illumination, detecting its presence or absence can be useful in gauging crop health and product ripeness or dryness. For instance, the technology can detect flaws, such as bruises under the skin of fruits passing by on an inspection line, that are invisible to the eye. Though perfectly suitable for many processed foods, bruises are not acceptable in fresh produce.
In textile processing, moisture detecting SWIR imagers are useful in the dyeing process. In particleboard manufacturing, online SWIR-based machine vision systems measure moisture in chips, and collected data is used to regulate heating and drying operations downstream.
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Viewing the apple in visible (left) and in SWIR (right) wavelengths demonstrates that bruises can be seen in the shortwave infrared and are not apparent in the visible. |
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