Abstract
The fast development in the fields of integrated circuits, photovoltaics, the automobile industry, advanced manufacturing, and astronomy have led to the importance and necessity of quickly and accurately obtaining three-dimensional (3D) shape data of specular surfaces for quality control and function evaluation. Owing to the advantages of a large dynamic range, non-contact operation, full-field and fast acquisition, high accuracy, and automatic data processing, phase-measuring deflectometry (PMD, also called fringe reflection profilometry) has been widely studied and applied in many fields. Phase information coded in the reflected fringe patterns relates to the local slope and height of the measured specular objects. The 3D shape is obtained by integrating the local gradient data or directly calculating the depth data from the phase information. We present a review of the relevant techniques regarding classical PMD. The improved PMD technique is then used to measure specular objects having discontinuous and/or isolated surfaces. Some influential factors on the measured results are presented. The challenges and future research directions are discussed to further advance PMD techniques. Finally, the application fields of PMD are briefly introduced.
Highlights
The three-dimensional (3D) shape measurement of objects is becoming increasingly important in many application fields
To measure free-form specular objects with a steep slope and/or large size, in recent years, deflectometry has been investigated by many researchers, which has led to the development of different deflectometric techniques, such as Moire deflectometry [19,20,21,22], the Ronchi method [23,24], phase-measuring deflectometry (PMD, called fringe reflection profilometry) using structured illumination of the surface [25,26,27,28,29,30], and laser scanning deflectometric techniques [30,31,32,33,34,35]
Two high frequency orthogonal fringe patterns and two single period orthogonal fringe patterns could be obtained from the composite fringe by a fast Fourier transform, which could be used to obtain the unwrapped phase by a heterodyne method
Summary
The three-dimensional (3D) shape measurement of objects is becoming increasingly important in many application fields. To measure free-form specular objects with a steep slope and/or large size, in recent years, deflectometry has been investigated by many researchers, which has led to the development of different deflectometric techniques, such as Moire deflectometry [19,20,21,22], the Ronchi method [23,24], phase-measuring deflectometry (PMD, called fringe reflection profilometry) using structured illumination of the surface [25,26,27,28,29,30], and laser scanning deflectometric techniques [30,31,32,33,34,35]. Deflectometric techniques do not need to locate the specular objects under investigation at a precise position These techniques overcome the shortcomings of interferometry to measure specular objects with a high dynamic range, it remains a challenge to reconstruct a specular surface shape by using deflectometric methods.
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