Method and Apparatus for Monitoring Blade Vibration With A Fiber Optic Ribbon Probe

In a turbine engine including a blade structure comprising a plurality of blades and blade tip target portions associated with the blades, and a casing surrounding the blade structure, a blade vibration monitor for monitoring blade vibration comprising:

• a light source;
• first and second illumination conduits each comprising a plurality of optical fibers arranged in a linear array and defining respective first and second transmission ends for locating adjacent to an interior portion of the casing for projecting an image of the light source onto the blade structure in the turbine, the projected image comprising an axially elongated projected image;
• a processor for processing reflected light images from a blade tip target portion corresponding to a blade passing event;
• and
• a detection conduit comprising a plurality of optical fibers arranged in a linear array and defining a receptor end, the detection conduit being configured to convey the reflected light images to the processor, and located adjacent to the transmission ends of the illumination conduits for receiving reflected light images from a plurality of locations along the axially elongated projected image during a blade passing event.

In a turbine engine including a blade structure comprising a plurality of blades and blade tip target portions associated with the blades, and a casing surrounding the blade structure, a method of monitoring blade vibrations comprising:

• emitting a line of light defining an axially elongated projected image from a plurality of illumination optical fibers;
• passing the blade tip target portions along a path of travel through locations corresponding to the axially elongated projected image and forming reflected light images at locations on the blade tip target portions to define blade passing events;
• and
• receiving the reflected light images at a receptor end of a detection conduit defined by a plurality of receptor optical fibers, the reflected light corresponding to a plurality of locations along the axially elongated projected image as each blade tip target portion moves past the line of light.