InGaAs Sensor Selection for Foreign Matter Detection
Select standard InGaAs for cost-effective detection up to 1700 nm, or cooled extended InGaAs to capture 2200 nm polypropylene combination bands cleanly.
Flat Field Calibration
Response Uniformity
Optical corrections compensate for variations in pixel sensitivity and uneven illumination across the field of view in automated inspection cameras. This flat field calibration ensures that a uniform target appears as a perfectly consistent gray value in the resulting digital image. Without this step, the edges of a fabric roll might appear darker than the center due to lens vignetting.
Mill environments use this process to normalize the performance of line scan cameras.
Image Correction
Lighting systems often provide more intensity at the center of the beam than at the periphery. Applying flat field calibration involves capturing a reference image of a neutral white or gray board and calculating a gain factor for every individual pixel. These factors are then applied to the live video stream to remove hardware artifacts.
This mathematical normalization allows the detection software to use a single threshold across the entire fabric width.
Maintenance Cycle
Accumulation of dust on the lens or degradation of the light source changes the required correction parameters. Operators perform a new flat field calibration whenever the camera height is adjusted or the light tubes are replaced. Routine checks prevent false alarms caused by static shadows or sensor drift.
Sorting Accuracy
Consistent image quality is necessary for the identification of small foreign objects in raw cotton. When flat field calibration is accurate, the contrast between a contaminant and the background fiber remains stable regardless of where the object appears under the camera. Precision in this step reduces the amount of good fiber accidentally rejected by the system.