In future versions of the inspection system, we plan to add the ability to inspect the heads of bone screws, allowing measurements of geometric and detection of debris. In addition, this optional feature will allow the system to read markings on the flanks of the screw head. In a single image, we obtain a “straight down” view into the head, as well as cleanly lit side views that allow the construction of a thee dimensional view.
The images for the head inspection are implemented using a unique catadioptric lens which consists of a center lens surrounded by a ring light. The ring light is surrounded by 6 front surface mirrors which are set at an acute angle to the center lens. This gives a center image surrounded by 6 images of the side walls of the cylinder. So in a few milliseconds, you can image the center of a cylinder and its side walls
An inspection system that supports head imaging requires both a second camera and robot. One robot holds the screw appropriately to image the threads. The second holds the screw in front of the specially lensed camera to obtain a 3D view of the head as viewed from the top. See these images for views of the one and two camera systems. If the system is provisioned with a color camera, color verification can be added to the inspection.
The following images demonstrate some of the features of the imaging.