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Research on Multi-wavelength and Multi-beam Illumination for
Improving Object Illumination Uniformity
Sun Quan, Ing Yu, Yang Yi, Yan Baozhu and Du Shaojun
College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China
Keywords: Illumination Uniformity, Multi-wavelength, Multi-beam, Atmospheric Propagation.
Abstract: The imaging and tracking to the far dim objects in the air are usually difficult for detecting system to get their
clear images and accurate positions, due to the objects neither emitting light nor reflecting sunlight. Using
active laser illumination technology, the target will be illuminated and the echo intensity of target can be
increased. The laser intensity spatial distribution on the target plane fluctuates usually remarkably due to the
atmospheric turbulence and other causes, which will decrease image resolution and tracking accuracy in
optical system. In this paper, we presented a method of using illumination with the supercontinuum spectrum
laser beam combination to improve the effect of target illumination uniformity. As the atmosphere
transmittance ratios differs with wavelength, we set up a multi-wavelength and multi-beam target illumination
simulation system to represent the supercontinuum spectrum laser illumination effect. As the previous
simulation results and the experimental results, which both reflect an improving effect of illumination
uniformity significantly by increasing of the beam number. The illumination uniformity of single beam with
multi-wavelength spectrum components was analyzed, and the simulation results of one single beam, three
beams and six beams with 9 wavelength spectrum were compared, which showed that the illumination
uniformity in target plane was improved with both the number of wavelength spectrum components and the
number of beams increasing. It showed that multi-spectral multi-beam illumination had great advantages in
improving illumination uniformity and the supercontinuum laser can be a good active illumination source.
1 INTRODUCTION
The imaging of and tracking to the far dim objects in
the air are usually difficult for detecting system to get
their clear images and accurate positions, due to the
objects not emitting light or reflecting sunlight. Using
active laser illumination technology, the target will be
illuminated and the echo intensity of target can be
increased. Active illumination with multi-beam has
been proved to be an effective technology to improve
the object illumination uniformity (Pavel et al., 2007)
(Quan et al., 2013) which can increase object image
resolution and tracking accuracy in optical system.
Supercontinuum (SC) laser sources have advantages
of wide spectrum range and good spatial coherence,
high brightness, better in direction. With the
increasing of the average output power (Song et al,
2013) (Xia et al, 2009), they become practicable in
many application areas, such as laser communication,
laser remote sensing, hyperspectral LiDAR, and laser
ranging (Alexander et al, 2012) (Hakala et al, 2012).
These applications all require SC laser sources
propagate through the atmosphere, meaning that the
beam will suffer atmospheric absorption, refraction,
extinction and turbulence effect (Kang and Wenyue,
2015) (Wuming et al, 2014). The wide spectrum of
SC laser propagating through atmosphere will be
separated into several main wavelength bands due to
the transmittance of different wavelengths. We use
SC laser as active illumination source means only the
wavelength bands which have high transmittance can
be valid for illuminating object. In this paper,
we presented a method of using the SC laser beams
combination as active illumination source to improve
the effect of target illumination uniformity. We set up
a multi-wavelength and multi-beam atmospheric
propagation and target illumination simulation
system. The simulation results showed that multi-
spectral multi-beam illumination had great
advantages in improving illumination uniformity.
120
Quan, S., Yu, I., Yi, Y., Baozhu, Y. and Shaojun, D.
Research on Multi-wavelength and Multi-beam Illumination for Improving Object Illumination Uniformity.
DOI: 10.5220/0007356301200124
In Proceedings of the 7th International Conference on Photonics, Optics and Laser Technology (PHOTOPTICS 2019), pages 120-124
ISBN: 978-989-758-364-3
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