Real-time computer-generated frequency-carrier Moire profilometry with three-frequency heterodyne temporal phase unwrapping

A real-time computer-generated frequency-carrier Moire ' profilometry with three-frequency heterodyne temporal phase unwrapping is proposed. While three sinusoidal gratings shared the same direct current(DC) component and the same amplitude but with designed different frequencies are projected onto the measured object, three corresponding deformed patterns can be captured by camera. Then, the shared DC component is extracted from the highest-frequency pattern. And based on it, three AC components of the captured deformed patterns can also be effectively extracted by normalization. From this way, the number of the needed gratings can be reduced from six to three, and the disturbance of the object's nonuniform reflectivity can be avoided efficiently. By using computer-generated frequency-carrier Moire ' profilometry(CGFCMP), the carrier frequency designed as pure si-nusoidal and cosinusoidal gratings is optimized in order to effectively extract the computer-generated frequency-carrier Moire ' fringes, and finally-three wrapped phases at different frequencies can be obtained. Then the wrapped phase with the highest-frequency grating can be unwrapped by three-frequency heterodyne temporal phase unwrapping algorithm. The simulation and experimental results verify the feasibility and flexibility of the proposed method. It is suitable to measure the complex surface with abrupt slope and multiple isolated objects, and has prospective application in real-time three-dimensional measurement.

Automated summary

This paper proposes a real-time computer-generated frequency-carrier Moire profilometry method with three-frequency heterodyne temporal phase unwrapping. By projecting three sinusoidal gratings with designed different frequencies but same amplitude and shared direct current component onto the measured object, corresponding deformed patterns can be captured and the DC component can be extracted. Then, by normalizing the extracted DC component, three AC components of the captured deformed patterns can also be effectively extracted. This method reduces the number of needed gratings from six to three and efficiently avoids the disturbance of object's nonuniform reflectivity.