Pulse-width modulation in defocused three-dimensional fringe projection.
Shape measurements by fringe projection methods require high-quality sinusoidal fringes. We present a sinusoidal fringe generation technique that utilizes slightly defocused binary fringe projection. The proposed method is a spatial version of the well-known pulse-width modulation (PWM) technique of electrical engineering. PWM is easy to implement using off-the-shelf projectors, and it allows us to overcome the gamma problem (i.e., the nonlinear projector response) in the output light intensity. We will demonstrate that, with a small defocusing level--lower than with other techniques proposed in the literature--a high-quality sinusoidal pattern is obtained. Validation experiments using a commercial video projector are presented.
Instituto de Física, Facultad de Ingeniería, J. Herrera y Reissig 565, Montevideo, Uruguay.
Gastón A
GA
Ayubi
Jaime A
JA
Ayubi
J Matías
JM
Di Martino
José A
JA
Ferrari