13.11.2015

Always go airborne safely

Vision & Control components help to check aero engine blades

Telecentric lens and LED bar light

A manufacturer of aero engine fan blades called upon the expertise of Fisher Smith, a service provider in the field of illumination and optics, to create a system to assist with the inspection of the main fan blades, which are used on its jet engines.

Instead of automatically processing images of the blades, the images should be captured, so that inspectors could manually determine and document the nature of any potential faults. Specifically for that task, Fisher Smith developed a custom PC-based vision system.

Prior to inspection, the heavy blade itself is mounted first with its root facing upwards into one of a number of fixtures, which can accommodate blades of different sizes and shapes. The PC-based system then captures images of the curved membrane at the root of the blade using a line scan camera, which is fitted with a T45/2.0L telecentric lens from Vision & Control. The telecentric lens ensures that the image magnification is independent of the distance of the root of the blade or its position in the field of view, enabling the camera to capture a 10mm wide image of the membrane at a resolution 0.005mm.

During the image acquisition process, a pair of Vision & Control LAL7-50/R-Ex red LED bar lights mounted on either side of the camera enclosure at a 10° angle illuminate a 10mm strip in the middle of the root of the blade. As the camera traverses the curved length of the blade, the images of the membrane of the blade are streamed to the PC-based system where they are stored for later analysis.