| Recently, phase-shifting fringe projection method develops very rapidly for optical profile measurement of objects with advantages of full-field, real-time, fast, non-contact and non-destruction. It can measure non-continuous surface with a low equipment requirements and has been widely used in aerospace, bio-engineering and military fields. With the development of computer DSP hardware technology, it has features of high-integration, high-speed, programmability and has a widely applications. In the present study, the fringe projection system has been combined with DSP technology. It will benefit for the instruments development of the three-dimensional morphology.Firstly, based on an introduction of the basic principles of fringe projection measurement techniques, single-frequency, dual-frequency and multi-frequency fringe unwrapping techniques are given and the relationship between the height and phase is discussed.Secondly, a computer controlled, dual-screen displayed projector&acquisition synchronization system was developed. It includes hardware and software systems. The hardware includes a projector, a CCD camera and other hardware devices. Software includes a projection&acquisition control software and a post-processing software. A plaster head was tested using the system and the relative error is only about3%. The buckling evolvements of a normal cardboard and a including45n crack cardboard were measured. The multi-frequency fringe projection method is a high precision, speed, full, non-destructive means.Finally, the combination of optical fringe projection with the DSP evaluation module is reasonable for the optical system with a faster, more portable equipment. A experiment of hand activities verified the feasibility of the DSP system. A fastest projection speed is up to10images per second with1024x768pixel. The system supports an automatic or manual observation of the projected image and multi-frequency fringes can be projected with a magnification ratio of10%-100%. |
