Research And Application Of PZT Phase Shifting System And Calibration Method

Phase measurement technique appeared in 1980s, which greatly improved the accuracy of optical metrology. With the data obtained in the testing field at the same time, the optical phase of full field testing is realized in deed associated with this technique. Phase-shifting is one of high accurate phase measurement technique. With less than one fringe in the field, the measurement also can be carried out efficiently by this way. The most common way to vary the phase is to apply phase modulation. The phase-shifter is the key component, whose accuracy directly effects the accuracy of phase measurement. Therefore the calibration of phase shifter is very important for the phase measurement.The phase-shifting system is developed on LabVIEW and PC1200DAQ combined with image capture software in VC. The calibration of this system with single detector can be applied to extensive situation of interferograms. Meanwhile, phase-shifting and calibration on the same optical setup is another advantage compared with other methods.Furthermore, in the circumstance of vibration and air turbulence, the expected value of phase shifting is hard to obtained. A novel method, which evaluates real-time phase variation between the two fringes based on digital correlation is presented. Interferograms are captured with accurate phase-shifting value even if the external turbulence exists.Based on researched phase-shifting system, a new method of five-step phase-shifting which can eliminate influence of PZT nolinearity on the precision of shifting by the relationship between micro-displacement and applied voltage is described.Meanwhile, the effective ways are introduced to decrease the influence of the characteristics of the PZT. For the creep, the continuous voltage is applied to the shifter, and continuous phase-shifting is obtained with creep effect itself. Moreover the zero-returned method is introduced to overcome the hysteresis, the coherent between phase-shifting and calibration is achieved.Finally, the system was applied to three-dimension profilometry and online phase-shifting lensless Fourier digital holography, the experimental results show the that phase-shifting system and calibration method developed in this paper can reach high accuracy and has widely application prospects in phase measurement technology..