Determination of the Height of 3D Objects by Moire Measurement

In the past, the height of objects was mostly measured by contact methods, and it may damage the objects. Fringe projection, as a new emerging measurement, might effectively improve the problem with the advantages of non-contact, non-destructive, real-time, full-field, and simple installation. This paper mainly discusses the fringe projection measurement technology to measure the height of the objects accurately. With the application of moiré projection, this paper explains the operation mode and theory of the fringe projection system, and then introduces the phase extraction and phase expansion of the sine wave fringe in sequence. With the longitudinal depth correction, a polynomial fitting method is used to establish a "phase-depth relationship", which is applied to the fringe phase to improve the depth measurement accuracy.