Study On Image Process And Phase Extraction For Fringe Projection Of Aero Engine Blades

With the rapid development of China’s aviation industry, aircraft engines are playing anincreasingly important role, and the blade is one of the most important parts of the aero engine.Accurate, real time measurement and repair of aircraft engine blades with the non-contact3Dmeasurement has broad application prospects, the field of aero-engine blades measuring repair hashot spots and the future trends.Aero engine blades as the object of study, use of non-contact the grating projectionmeasurement study of the advantages of the full-field, high-precision and fast.First, according to the measuring principle of the cross the optical axis of the system, builda monocular measurement system hardware platform, mainly by the projection device, a CCDcamera, computer. Computer generated standard sinusoidal fringe. According to the principles ofthe phase measurement, using four-step phase shift method phase extraction, and software toachieve precise phase shift, get four-step phase shift.Then, use color space conversion method to suppress high reflective part of the blades.Followed by using the best fringe frequency selection method to select the three differentfrequencies, respectively, projected onto the measured blades, four images as a group, extractionphase, and finally to obtain three different frequencies wrapped phase. Phase unwrapping usingmulti-frequency fringes expand image, eventually get the continuous expansion phase.Followed by the camera and the system calibration, the use of the virtual plane can beflexible and free use of the advantages to achieve calibration at an arbitrary position, to improvemeasurement efficiency. Finally, obtain the relationship between the height of the object pointand measurement system. The relation, obtained from the unwrapped phase and the previouslysystem calibration data, can be obtained three-dimensional data of the measured blade.