Phase calculation-based fringe projection techniques are widely used in three-dimensional shape measurement fields to obtain the 3D shape data of the object’s surface. One important step of the phase calculation is calibration, which determines the relationship between the image phase and depth information. The traditional calibration methods are too complex and require many parameters. In this paper, model of 3D shape precision calibration method based on non-diffraction grating structured light fringes projection is proposed, which is consist of camera model, fringe phase obtaining, height-phase relationship model. This method is simple, convenient and there is no approximation in it, which can satisfy the precision measurement.
The accuracy of stylus profilometer sensor directly affects the performance of the profilometer. To ensure good status of the profilometer, the accuracy features of the profilometer sensor should be verified regularly. However by now, only standard samples with comprehensive parameters are adopted for verification of the total profilometer, and there is no verification device for stylus profilometer sensor, especially for that with large range and high resolution. In this paper, a special verification device for stylus profilometer sensor is introduced. The device consists of displacement generation unit, displacement measurement unit and data acquisition and feature analysis software unit. A motor and PZT are combined to be a large range and high resolution displacement generator in the displacement generation unit, and a grating interference displacement measurement unit gives standard value of the displacement. When a sensor should be verified, the displacement generation unit generates displacement within the measuring range of the stylus sensor, and the displacement is input to the sensor, the output of the senor is compared with the data measured by the grating interference displacement measurement unit, and the acquisition and feature analysis software unit shows the accuracy features of the stylus sensor. A double frequency laser interferometer is applied to the verification device for experimental testing, its high accuracy, stability, reliability and wide range is verified, which satisfies the large-scale verification requirement of stylus profilometer sensor.
Small angle measurement has been widely use for the alignment or error compensation of a mechanical system. In this paper a small angle dynamic measurement device based on laser interference technique is introduced, which consists of a reference module and a measuring module. The measuring module is fixed on the measured object. With the variation of the small tilt angle of the measured object, the phase difference between the two beams from prism1 and prism2 changes according to it. By analyzing the interference patterns, the variation of the small tilt angle can be obtained dynamically. Experimental setup has been established and the results show that the measurement range is 15' with the resolution of 0.08", the measurement error is less than 8″.
A new optical configuration for amplified off-axis digital holographic microscopy is presented and applied to surface measurement. By symmetrical configurations in the optical path, aberration compensation for phase curvature can be avoided in the reconstructed process. Three dimensional surface texture of a grating plate is reconstructed via a single hologram and its parameters are verified.