BORESCOPE WITH HOLOGRAPHIC TESTING CAPABILITY
Publication Date: 2016-May-19
The IP.com Prior Art Database
On-wing inspection of aircraft parts is done primarily using 2D image information, which is insufficient for assessing most defects. The invention describes a borescope with holographic testing capability for inspection of aircraft engines. The holographic borescope uses two laser beams, one to illuminate the component, and the other to provide a reference. A camera sensor placed near the tip of the borescope receives a holographic image of the component with interference patterns via a lens and a pixelated mask. The interference patterns are used to create a holographic recording. The component is then given acoustic excitation while recording the holograph, which is characteristic of how the part vibrates or bends. The holographic pattern reveals any cracks or defects present in the component. The invention provides a rapid means of identifying defective aircraft engine components with a high degree of confidence using a portable device, thereby saving costs.
The invention relates to inspection techniques in general, and to a borescope with holographic testing capability for on-wing inspection in aircraft engines, in particular. On-wing inspection of aircraft parts is done primarily using visual 2D inspection through a borescope. However, this 2D image is insufficient to decide whether the aircraft engine needs to be unmounted and disassembled due to some structural defect in a part. A visual indication appearing in the 2D image may later on turn out to be harmless. The limitations of conventional borescope inspection therefore illustrate the need for a better inspection method.
BRIEF DESCRIPTION OF DRAWINGS
The invention discloses a borescope with holographic testing capability for on-wing inspection in aircraft engines.
FIG. 1 shows a schematic view of the borescope with holographic testing capability.
FIG. 2 represents typical interference patterns by using holographic borescope inspection of an aircraft engine.
The invention describes a borescope with holographic testing capability for on-wing inspection in aircraft engines, as illustrated in FIG. 1. The holographic borescope has two laser beams coming in, one to illuminate the subject, and the other to provide a reference beam. A camera sensor is placed near the tip of the borescope and receives the subject image via a lens and a pixelated mask. The reference beam passes through a beam splitter that splits this beam to both illuminate the subject, which may be an engine component such as a turbine and send a small, reference beam directly to the video sensor. The pixelated mask on the camera sensor splits the resulting interference between the reference beam and that light reflected from the part so as to produce 4 phases of interference patterns. These 4 phases of patterns are then used to create a holographic recording of the part being inspected. By providing some small excitation to the part such as by a sound wave, an interference pattern is generated, that outlines how the part vibrates or bends, as illustrated in the left side image shown in FIG. 2. In case of defect, the pattern shows irregularities, as illustrated in...