US Patent 7502128 Monitoring arrangement for rotating components

There are difficulties with regard to observing a rotating component in an obscuring environment such as typical of a gas turbine engine where there may be soot, flames, light signals and moisture. It will be understood that simply increasing the light intensity will increase scatter and therefore may “blind” a camera in terms of viewing distinctive features and targets within a rotating component. The present arrangement provides a mirror with an aperture such that an illuminating light source is directed towards a rotating component such that reflection is similarly incident upon the reflective mirror and light deflected to the camera. In such circumstances the camera is less susceptible to light scatter obscuration.