Abstract
This paper describes a computational 3-D imaging system based on diffraction grating imaging with laser sources of multiple wavelengths. It was proven that a diffraction grating imaging system works well as a 3-D imaging system in our previous studies. The diffraction grating imaging system has advantages such as no spherical aberration and a low-cost system, compared with the well-known 3-D imaging systems based on a lens array or a camera array. However, a diffraction grating imaging system still suffers from noises, artifacts, and blurring due to the diffraction nature and illumination of single wavelength lasers. In this paper, we propose a diffraction grating imaging system with multiple wavelengths to overcome these problems. The proposed imaging system can produce multiple volumes through multiple laser illuminators with different wavelengths. Integration of these volumes can reduce noises, artifacts, and blurring in grating imaging since the original signals of 3-D objects inside these volumes are integrated by our computational reconstruction method. To apply the multiple wavelength system to a diffraction grating imaging system efficiently, we analyze the effects on the system parameters such as spatial periods and parallax angles for different wavelengths. A computational 3-D imaging system based on the analysis is proposed to enhance the image quality in diffraction grating imaging. Optical experiments with three-wavelength lasers are conducted to evaluate the proposed system. The results indicate that our diffraction grating imaging system is superior to the existing method.
Highlights
Three-dimensional (3-D) imaging plays a key role in 3-D techniques
We introduce the analyses of the spatial period of each parallax image array, the depth resolution, and the parallax angle according to each wavelength, which are given as generalized formulas and data tables
Since the spatial period is a key parameter in the 3-D computational reconstruction process, it is necessary to calculate the spatial periods for one depth according to multiple wavelengths and it needs to integrate the 3-D images obtained from the parallax image arrays of multiple wavelengths
Summary
Three-dimensional (3-D) imaging plays a key role in 3-D techniques. their application fields are very broad such as augmented reality, autonomous driving, entertainment, defense, and biomedical imaging [1,2,3,4,5,6]. A suitable computational reconstruction technique for diffraction grating imaging is required since there is no pattern to distinguish between parallax images in the captured PIA [20]. We propose a diffraction grating imaging system to reduce the problems of the system and to improve the image quality, employing multiple lasers with different wavelengths. The parallax image arrays have different characteristics, depending on the nature of the wavelengths of the lasers This means that the wavelength affects the image quality of the reconstructed 3-D image; it is worth studying a diffraction grating imaging system, taking the multiple wavelengths of the lasers into account. We propose a 3-D computational reconstruction method where multiple 3-D images from the parallax image arrays are integrated into a 3-D image. Optical experiments with lasers of three different wavelengths are conducted and the results are compared with the existing method subjectively [20]
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