Optical Fiber Space Encoding Projector Design And Applied Research

Optical 3-D non-contract measurement technique has potential andadvantages for 3-D sensing.It has been widely used due to fast of examination,high accuracy of determination and automatization of data processing.In thisinvestigation,optical fiber interferometer was adopted to build the structure-lightprojector by using multi-optical fiber space coding and dual-core optical fiber.Several kinds of interferogram are produced by optical fiber interference.Basedon optical fiber space coding projector,optical fiber frequency conversion,mixingfrequency,frequency shift,reference fringe phase shift methods were developed,also the numeric simulation results and experiment research are given.Severalkinds of structural parameter of the projector are discussed in order to understandthe influence of the structural parameter on measurement range and precision.Theresult of numerical simulation and experiment research show that optical fiberinterference projector is feasible and valid for object's shape.The research showsthat the object's profile can be reconstructed by the methods of optical fiberfrequency conversion or mixing frequency,if the structural parameter of theprojector was selected reasonably and the overlap of the frequency spectrum wasaverted.The error transmission can be averted by this time domain phaseunwrapping method.Thus the surface of the object with sharp edges may bemeasured.The phase was detected by one fringe pattern.This method can meetthe needs of dynamic state and current time measurement.The 3-D profilometrybased on reference fringe phase shift methods needs only a carrier frequencyimage to reconstruct the profile of the tested object.Four frames reference imagewith accurate and equal pace phase shifting may be obtained by the computer. Therefore phase shifter was saved.This method can improve measurementaccuracy and be fit for current time measurement,but also the zero-frequencycomponent of the image was wiped out.The measurement limit was enlarged andthe ability in anti-disturbance was improved.The multi-optical fiber space coding projector has several advantages,forinstance,laser diode (LD) is used in this system.And it is compact and stablecompared with other laser interferometer systems.The size of optical fiberprojector is small and it is easy to operate to adjust the space period andorientation,hence the data fusion technique is easily carried out.Especially,thisprojector is suitable extremes environment such as very narrow place or smallhole.This study work expands structure-light projecting method.It has referentialmeaning on depth study and actual application of multi-optical fiber interference3-D profilometry.