Real-time turning surface inspection using laser light scattering

An optical system for real-time measurements on a turning surface was designed and implemented in the optical metrology laboratory at CICATA-IPN. Different profiles of machined parts can be determined using a single detector or a photo-diode array. The basis of the measurement is the scattering of a laser beam which is reflected by the turning surface. Two different configurations were tested, the first one uses a single photodetector and a commercial lock-in amplifier, and the second uses a photodetector array and a proprietary platform. The samples under test were mounted on two different lathes for each configuration. The samples were rotating while the measurements were taken by the electronic system. Under these conditions it was possible to detect the intensity changes of the scattered light in the single detector case, and changes of the spread in the intensity distribution in the multidetector case. With the acquired data, qualitative profiles of the samples were obtained, with promising results. Potential applications in industry are straightforward when surface inspection is necessary to asses product's quality. © 2009 SPIE.