Simultaneous measurement of three-dimensional displacement gradients using tri-color Michelson-type digital shearography: comparison and optimization of optical setups Beijing Info. Sci. and Tech. Univ

Format:

Book

Conference/Event

Author/Creator:

Wang, Huiying, author.

Contributor:

Li, Weixian

Wu, Sijin

Conference Name:

SAE WCX Digital Summit (2021-04-13 : Live Online, Pennsylvania, United States)

Language:

English

Physical Description:

1 online resource cm

Place of Publication:

Warrendale, PA SAE International 2021

Summary:

Digital shearography is one of the important non-contact optical measurement techniques. Due to its characteristics of full-field, non-contact, high-resolution, high-stability and dynamic measurement, digital shearography has become a competitive candidate for measurement of surface displacement gradient. Reliable displacement gradient measurement provides useful data for the management, improvement and application of materials. Especially the simultaneous measurement of multidimensional displacement gradients is more meaningful, because it can provide more comprehensive information to evaluate the performance of material and device. The multidimensional displacement gradients can be effectively determined by the use of spatial-carrier tri-color Michelson-type digital shearography. When different kinds of camera are used in the optical setups, the frequency spectrums are quite different. Three high-frequency components appear on a single frequency spectrum when a black and white (B/W) camera is used. These three high-frequency components are separated into three individual spectrums when a color camera is used. The three pairs of high-frequency components on the B/W camera spectrum are very prone to aliasing. This makes the adjustment of optical paths difficult. On the contrary, there is only one pair of high-frequency components on the spectrum, so it is easy to build the optical setup. The B/W system exceeds the color system in phase map quality. Since color camera uses Bayer filter to allow different elements to absorb corresponding light and interpolation method to calculate the RGB information of each pixel, it is inevitable that some image information is lost. This problem does not exist in the B/W system. Therefore, when the pixel number of the image sensor is the same, the image resolution of B/W camera is better than it of the color camera. Moreover, according to the color camera response curve, a problem of crosstalk between R, G and B channels exists. The three light beams with different wavelength enter into other channels in different degrees, affecting the quality of the phase map

Notes:

Vendor supplied data

Publisher Number:

2021-01-0302

Access Restriction:

Restricted for use by site license