Open AccessDouble-pattern triangular pulse width modulation technique for high-accuracy high-speed 3D shape measurement
Author(s) -
Yajun Wang,
Chufan Jiang,
Song Zhang
Publication year - 2017
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.25.030177
Subject(s) - binary number , optics , phase (matter) , modulation (music) , pulse width modulation , pulse (music) , phase modulation , pixel , signal (programming language) , binary data , structured light 3d scanner , computer science , physics , mathematics , acoustics , detector , phase noise , arithmetic , scanner , quantum mechanics , voltage , programming language
Using 1-bit binary patterns for three-dimensional (3D) shape measurement has been demonstrated as being advantageous over using 8-bit sinusoidal patterns in terms of achievable speeds. However, the phase quality generated by binary pattern(s) typically are not high if only a small number of phase-shifted patterns are used. This paper proposes a method to improve the phase quality by representing each pattern with the difference of two binary patterns: the first binary pattern is generated by triangular pulse width modulation (TPWM) technique, and the second being π shifted from the first pattern that is also generated by TPWM technique. The phase is retrieved by applying a three-step phase-shifting algorithm to the difference patterns. Through optimizing the modulation frequency of the triangular carrier signal, we demonstrate that a high-quality phase can be generated for a wide range of fringe periods (e.g., from 18 to 1140 pixels) with only six binary patterns. Since only 1-bit binary patterns are required for 3D shape measurement, this paper will present a real-time 3D shape measurement system that can achieve 30 Hz.