3D Shape Measurement Using Fiber Optic Interference Fringe Projection With Integrating Bucket Modulation

Optical 3D shape measurement technique is an important means of object shape measurement,which was becoming a hot research topic that focuses on dynamic and high-precision phase profile measurement technology.In this paper,we develop a new method of fiber interferometer fringe projected three-dimensional shape measurement based on the large sinusoidal phase modulation integrating bucket.This method makes use of the laser inner-modulation technique to achieve precise measurement and modulates the signal of PZT or the current of the laser to modulate the interferometric phase;takes advantage of Mach-Zehnder interferometer structure and Young's double pinhole interference principle to achieve interference fringe projection.We utilize Fresnel reflection signal to realize phase modulation precise control and the measurement of PGC-based interference phase difference,finally get access to wrapped phase map quickly.We employ phase unwrapping technology and combine with optical interference fringe projection model to restore the 3D topography information.The main contents of this paper are as follows:1?We analyze 3-D profilometry using fiber-optic interference fringe projection.Its measuring principle,mathematical model and phase modulation method are described.An interference fringe projector based on Mach-Zehnder interference structure and Young's double-pinhole interference is proposed and the method of phase demodulation is illustrated.The major factors leading to interference phase unstability are analyzed,and accordingly a feedback system based on the Michelson interference signal caused by the Fresnel reflection light of the fiber ends.2?We present a fiber-optic interferometer fringe projector with sinusoidal phase shifting interferometry based on modulating the signal of piezoelectric transducer(PZT).The system utilizes sinusoidal phase shifting interferometry to detect the desired phase which is improved by introducing constant scaling factors from linear phase shift interferometry algorithm,example algorithms demonstrate specific design principles and offer optimum constant scaling factors.We dicuss the phase modulation coefficient and the relationship between the modulation voltage and the phase modulation coefficient is analyzed;the system also utilizes the reflection signal to realize measurement of the disturbance and feed back to the modulated signal to stabilize the system.3?we present a sinusoidal phase-modulating fiber-optic interferometer fringe projector by modulating signal of laser.Here,we consider the modulated signal with the modulation intensity of laser(companion amplitude modulation)in the Integrating-Bucket calculation directly,adjust the optimal value of z to accommodate different m,and calculate the initial phase with PGC technology at the same time.The system utilizes Fresnel reflection signal to realize the measurement of the disturbance and feed it back to the modulated signal of laser at the same time.The continuous signal truly reflects the error information Practical experiments validate the feasibility of this method.4?An experimental system based on fiber-optic interference fringe projection is constructed on a shock-proof optical platform,taking advantage of an external phase modulation method based on piezoelectric transducer.The parameters of the major devices are analyzed;a high voltage drive circuit to drive the piezoelectric ceramic system is designed and its performance is studied;By measuring the 3d profiles of an aluminum plate,a circular mold and a convex slot,the stability and accuracy of the measurement system are analyzed.