Open AccessCombination of micro-scanning mirrors and multi-mode fibers for speckle reduction in high lumen laser projector applications
Author(s) -
Zhaomin Tong,
Wenjiang Shen,
Shao-Hua Song,
Wenzhi Cheng,
Chen Zhuo,
Yifei Ma,
Lei Wei,
Weiguang Ma,
Xiao Liu,
Suotang Jia,
Xuyuan Chen
Publication year - 2017
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.25.003795
Subject(s) - optics , speckle pattern , laser , materials science , raster scan , laser scanning , numerical aperture , aperture (computer memory) , optoelectronics , physics , wavelength , acoustics
In high lumen laser projectors, it is required to use laser diodes coupled to multi-mode fibers (MMFs) to obtain a high power illumination module. In this paper, we have fabricated an electromagnetic micro-scanning mirror (EM-MSM), and we have firstly demonstrated a speckle reduction method by the combination of the EM-MSM and the MMF. With the help of a condenser lens, laser beams modulated and reflected from the EM-MSM are coupled into the MMF within its acceptance angle. Because the fast scanning behavior of the EM-MSM results in the phase modulation and mode coupling among the MMF guided modes, the light intensity field distributions at the exit aperture of the MMF are changing. During the charge-coupled device (CCD) integration time, the random speckle patterns are integrated and homogenized by the CCD camera, and hence speckle is reduced. By driving the EM-MSM in raster scan, the lowest compound speckle contrast ratio at 0.0794 is obtained, where the EM-MSM half scanning angles are 0.4 ° and the optical power loss is lower than 4.5%. The demonstrated technique is compact and can endure the high power of the laser module; thus, it has a promising potential in high lumen laser projector applications.