COL Cover Story: Three-dimensional imaging lidar system based on high speed pseudorandom modulation and photon counting
At: 2016/11/21 8:39:00 by admin

Laser radar technologyhas been developed rapidly since the advent of laser. Among various laser radars,the three-dimensional (3D) imaging lidar has been of great concern. Thetraditional 3D imaging radar based on direct detection mode has two main ways:The first method is to use a single pulse of high peak power for time-of-flightranging. This method requires a laser capable of producing pulsed laser with highpeak power and narrow pulse width, which is expensive and difficult tomanufacture and cannot be miniaturized. Thesecond approach is to use time-correlated single-photon counting techniques.Although this method can work with low peak power laser pulses, it requires along pixel dwell time to establish the distribution of photoelectrons, whichseriously reduces the imaging speed.

In order to overcome theabove problems, the research team led by Chen Weibiao from Shanghai Instituteof Optics and Fine Mechanics, Chinese Academy of Sciences, carried out theresearch of 3D imaging lidar based on high-speed pseudo-random code modulationand photon counting, and verified it in outdoor environment. Related researchresults are published in Chinese Optics Letters, Volume 14, No. 11, 2016 (Y. F.Zhang, et al., Three-dimensionalimaging lidar system based on high speed pseudorandom modulation and photoncounting).

The principle of the 3Dimaging lidar based on high-speed pseudo-random code modulation and photoncounting is as follows: Pseudo-random codes have sharp autocorrelation valueand very low cross-correlation value, so the position of pseudo-random codescan be extracted from noise by correlation operation. The target distance canbe obtained by calculating the time between the transmitting and receiving ofthe modulated laser. In this method, low power emission and single photonreception are adopted. Both the peak power requirement of the laser and thepixel dwell time are reduced. The advantages of low peak power and high imagingspeed make it possible to reduce the size and power consumption of the systemwithout sacrificing the imaging speed.

The results of theoutdoor imaging with the target distance of 1.2 km are reported in this paper,and high-quality 3D images are obtained. Prof. Chen Weibiao believes that theadvantages of high sensitivity and high imaging speed the technology possessesmake it suitable for long-distance three-dimensional imaging and detection,such that the technology has a great development potential.

Further work is toachieve system miniaturization and low power consumption and to enhance SNR inthe high noise level conditions.

Graphic description: Set-up and imagingresults of three-dimensional imaging lidar system adopting the high speedpseudorandom modulation and photon counting techniques. With the advantages oflow peak power emission and high imaging speed, high-resolutionthree-dimensional images of the targets in the range of 1.2 km have been successfullyobtained by the system.

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