Single-shot detection of 8 unique monochrome fringe patterns representing 4 distinct directions via multispectral fringe projection profilometry

Parsa Omidi,Mamadou Diop,Mohamadreza Najiminaini,Jeffrey J L Carson

doi:10.1038/s41598-021-88136-4

Parsa Omidi, Mamadou Diop + Show 2 more

Open Access

https://doi.org/10.1038/s41598-021-88136-4

Copy DOI

Abstract

Spatial resolution in three-dimensional fringe projection profilometry is determined in large part by the number and spacing of fringes projected onto an object. Due to the intensity-based nature of fringe projection profilometry, fringe patterns must be generated in succession, which is time-consuming. As a result, the surface features of highly dynamic objects are difficult to measure. Here, we introduce multispectral fringe projection profilometry, a novel method that utilizes multispectral illumination to project a multispectral fringe pattern onto an object combined with a multispectral camera to detect the deformation of the fringe patterns due to the object. The multispectral camera enables the detection of 8 unique monochrome fringe patterns representing 4 distinct directions in a single snapshot. Furthermore, for each direction, the camera detects two π-phase shifted fringe patterns. Each pair of fringe patterns can be differenced to generate a differential fringe pattern that corrects for illumination offsets and mitigates the effects of glare from highly reflective surfaces. The new multispectral method solves many practical problems related to conventional fringe projection profilometry and doubles the effective spatial resolution. The method is suitable for high-quality fast 3D profilometry at video frame rates.

Highlights

Spatial resolution in three-dimensional fringe projection profilometry is determined in large part by the number and spacing of fringes projected onto an object
The multispectral filter array (MFA) was comprised of a 2 × 2 arrangement of square bandpass filters that was repeated in a 2D Bayer-like pattern[35,36]
An image of the MFA was focussed onto the target using a 20 × microscope objective resulting in a multispectral dot pattern that completely covered the target

Summary

Introduction

Spatial resolution in three-dimensional fringe projection profilometry is determined in large part by the number and spacing of fringes projected onto an object. Capturing more patterns leads to more accurate phase estimates, but the sequential projection of the patterns lengthens acquisition time and may not be suitable for highly dynamic measurements[2] This situation has motivated many groups to develop methods to improve the speed of FPP through the use of fast switching digital projectors that cast fringes using monochromatic or RGB colored light[3,4,5,6,7,8,9]. The method provided the necessary object data to take advantage of robust reconstruction algorithms that implement π-phase shifted fringe patterns, but with the advantage of acquiring the data in a single camera exposure with a single light source from a single projection coordinate. We introduce the multispectral fringe pattern profilometry (MFPP) method and provide the first performance tests

Methods

Results

Conclusion