Algorithm for phase shifting shadow moiré with an unknown relative step

et al. 2013

Appl. Opt.

Self Cite

We present a fast phase-shifting shadow moiré device for surface topography measurement. In our setup, multiple light sources located at different positions are controlled to illuminate the grating sequentially. Therefore, the phase shift across the field of view shadow moiré is introduced by changing the distance between the light source and the camera. Thanks to the necessity for mechanical movement being omitted here, the proposed setup can capture the phase-shifting fringe patterns at a high speed. However, affected by the bias modulation and amplitude modulation of the captured fringe patterns, the phase of interest cannot be demodulated by the standard phase-shifting algorithm directly. Thus the principal component analysis (PCA) demodulation approach is used to extract the wrapped phase map. In addition, we develop an iterative procedure to reduce the detuning error introduced by the PCA algorithm. The proposed method implements a fast way to determine the topography of a surface through a simple experimental setup. It is applied to obtain an external surface of a specimen. Both the simulation results and the experimental results show the validity of the proposed technique.

“…7(a). We also test the spherical surface by the method proposed in [9] and the reconstructed surface is shown in Fig. 7(b).…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Shadow moiré technology based fast method for the measurement of surface topography

et al. 2013

Appl. Opt.

Self Cite

“…1,2 To deal with it, numerous detuning-robust [3][4][5] and selfcalibrating 6-10 algorithms have been developed to retrieve the precise phase map during the last several decades. Recently, we proposed a method based on iterative technique 15,16 to allow good phase estimation even with nonsinusoidal shadow moiré fringes. This assumption is too strong to be met in a shadow moiré because uniform phase shifts across the field of view of shadow moiré are impossible.…”

Section: Introductionmentioning

confidence: 99%

Phase extraction from random phase-shifted shadow moiré fringe patterns using stereovision technique

Wang

et al. 2014

Opt. Eng

Self Cite

The measurement accuracy of phase shifting shadow moiré is affected by both the spatially nonuniform phase shift error and random phase shift error. Substantial work has been done to overcome this difficulty, but few works can deal with the two error sources simultaneously. In the presented paper, we describe a solution that can compensate for the two error sources at the same time. In our method, a binocular stereovision system is integrated into a shadow moiré configuration to calibrate the setting parameters. Thus, a precise measurement setup is built. Then, we developed an iterative least-squares algorithm to analyze the acquired three fringe patterns. The proposed algorithm can extract the measurement phase without nonuniform phase shift error. On the other hand, it can compensate the random phase shift error by calibrating the distance of grating translation using the least-squares fitting in spatial. Optical experiments show that the proposed method can effectively minimize the phase-shift error and that it possesses a superior performance than the existing typical phase shifting algorithm. Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 05/16/2015 Terms of Use: http://spiedl.org/terms

“…A good general overview of the technique can be found in 4 . But the problem has recently been solved with an iterative approach 5,6 . And the application of PSSM technique is expanded with no addition the complication of the experimental set-up.…”

Section: Introductionmentioning

confidence: 99%

Fast phase shifting shadow moiré by utilizing multiple light sources

2013

SPIE Proceedings

Self Cite

We present a fast phase shifting shadow moiré device for the measurement of surface topography. In our set-up, the phase shift across the field of view shadow moiré is introduced by using two light sources illuminate the grating sequentially. Therefore, it is possible to capture the two fringe patterns at high speed. Due to the effect of bias modulation, the proposed phase demodulation method first removes the DC term of the sampling data. Then a spiral phase transform (SPT) based technique is developed to determine the introduced phase shift pointwisely. After that, the tunable two-frame algorithm is used to extract the wrapped phase map with no spatially non-uniform phase shift error. We implemented a fast technique to determine the topography of a surface by a simple experimental set-up. The proposed technique was applied to obtain an external surface of a specimen. The experimental results show the validity of this technique.