Surface Contour Measurement Using a Short Range Laser Displacement Sensor

Non-contact freeform surface measurement is widely used in industry. To acquire the surface data, a laser displacement sensor and a motion system are typically used. One of the factors that affect the measuring accuracy is the sensor’s resolution. A high resolution sensor usually has a short measuring range. However, an unknown component’s profile with a large peak-to-valley height variation can not usually be measured using a short range sensor. We designed and developed a measuring system based on an existing 3-axis motion system with a laser displacement sensor mounted on its Z axis. This measuring system can be easily integrated to an existing laser processing system by standard communication ports to extend its applications into tool path planning, in-line inspection and monitoring. With the developed system, the real-time distance from the sensor to the component surface is acquired, and used as a feedback signal to control the sensor’s position on the Z axis to automatically maintain its distance with a given value. Through this development, the measuring range of the system is extended from the sensor’s measuring range up to the Z axis travelling range of the motion system so that a surface with large peak-to-valley height variation can be easily measured by a short range sensor with substantially improved accuracy.Mechanical Engineerin