Optical 3-D dynamic measurement system and its application to polymer membrane inflation tests

• Published in: Optics and lasers in engineering 2000-04, Vol.33 (4), p.261-276
• Main Authors: Li, Yong, Nemes, James A, Derdouri, A
• Format: Article
• Language: English
• Subjects: 3-D coordinates measurement; Calibration; Exact sciences and technology; Fourier transform; High-speed techniques (microsecond to femtosecond); Laboratory procedures; Measurements common to several branches of physics and astronomy; Membrane inflation test; Metrology, measurements and laboratory procedures; Physics; Spatial dimensions (e.g.: position, lengths, volume, angles, displacements, including nanometer-scale displacements); Spatial dimensions (eg, position, lengths, volume, angles, displacements, including nanometer-scale displacements)
• ISSN: 0143-8166; 1873-0302
• DOI: 10.1016/S0143-8166(00)00047-6

An optical surface measurement system, which is capable of measuring transient surface shape, has been developed by using a high-speed digital camera. The system is based on the grating projection and Fourier transform technique. A calibration procedure is developed to allow the system to generate Cartesian coordinates directly, which are with respect to a fixed coordinate system in 3-D space. The measurement accuracy (±50 μm) is defined and verified as the maximum error between measured values and the known values of standard objects both flat and curved. The camera and a grating projector are mounted into a portable sensor head to allow in situ measurements. In addition, external force or pressure signals can be correlated with each measurement through a device called the multi-channel data link. The system is capable of digitizing a 3-D curved surface into an array of points with known xyz coordinates at a sampling rate from 30 to 1000 Hz. As an application, the system is used to measure the transient surface shape during a polymer membrane inflation test. The measurement results along with the pressure information provide an approach to determine the material parameters used in different material models.