Virtual fringe projection system with nonparallel illumination based on iteration

Abstract

Fringe projection profilometry has been widely applied in many fields. To set up an ideal measuring system, a virtual fringe projection technique has been studied to assist in the design of hardware configurations. However, existing virtual fringe projection systems use parallel illumination and have a fixed optical framework. This paper presents a virtual fringe projection system with nonparallel illumination. Using an iterative method to calculate intersection points between rays and reference planes or object surfaces, the proposed system can simulate projected fringe patterns and captured images. A new explicit calibration method has been presented to validate the precision of the system. Simulated results indicate that the proposed iterative method outperforms previous systems. Our virtual system can be applied to error analysis, algorithm optimization, and help operators to find ideal system parameter settings for actual measurements.

Performance analysis and evaluation of direct phase measuring deflectometry

“…The relationship between point ARH on plane H and point AR on plane R can be obtained using the iterative method given in [21]. This then allows the height, the gradient and the gradient angle of point ARH on plane H to be obtained.…”

“…The resolution of the CCD chip is XL×YL and the physical size of a single pixel unit on the CCD chip is dc×dc. The formula required to calculate the coordinates on the reference plane R based on the coordinates on the projection plane is deduced by the method described in [21]. Because the CCD camera has a similar optical framework to that of a digital light processing projector, the relationship between point AR on plane R and point ARS on plane S can be obtained using the following equations.…”