A camera and laser team up to measure screw threads to 0.0423 mm precision.

Screws hold machines together, so their shapes must be exact. Checking them by touch is slow and measures very few spots. Standard optical scanners work without touching, but their scattered data points struggle to map sharp edges accurately. To solve this, researchers built a system combining a laser scanner and a camera. The laser scans the screw to make a three-dimensional point cloudpoint cloudA collection of 3D points that represent the surface of an object., which is a digital shape made of millions of tiny dots. Meanwhile, the camera pinpoints the screw thread edges with fine detail. A joint process uses those sharp camera edges to fix the positions of the three-dimensional points along the thread crests. Finally, a step-by-step pipeline calculates the pitch, which is the distance between threads. Tests on a real screw showed an error of just 0.0423 mm.

Why it matters

Screws hold together everything from engines to electronics, and tiny measurement errors can cause failures. Traditional inspection is slow and only checks a few points. This method uses a camera and laser together to measure every thread accurately and quickly, making quality control more reliable.

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