scholarly journals Portable Pulsed Coherent Lidar for Noncooperation Targets at the Few-Photon Level

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2341
Author(s):  
Chengkai Pang ◽  
Qiongqiong Zhang ◽  
Zhaohui Li ◽  
Guang Wu
Keyword(s):  
High Sensitivity ◽  
Coherent Detection ◽  
Laser Ranging ◽  
Phase Plate ◽  
Superposition Method ◽  
Echo Signal ◽  
Long Distance ◽  
Measurement Rate ◽  
Decoherence Effect ◽  
Coherent Lidar

The decoherence in coherent lidar becomes serious with the increase in distance. A small laser spot can suppress the decoherence of the echo light from noncooperation targets. However, it is very difficult to keep a small light spot over a long distance. In this paper, a pulsed coherent lidar with high sensitivity at the few-photon level was demonstrated. A phase plate was used to modulate the wavefront of the laser to achieve 100 m focusing which reduced the decoherence effect. Based on coherent detection and time-of-flight (TOF) measurements, long-distance laser ranging and imaging on all days was realized. A signal classification and superposition method was used to extract the echo signal submerged in noise. The system was experimentally demonstrated by ranging different noncooperation targets within 105.0 m. The measurement rate was 10 k/s, and the measurement uncertainty was 1.48 cm. In addition, laser imaging was realized at ~50.0 m. The system was simple and portable as well as eye safe, and it may offer new application possibilities in automated vehicle lidar.

Photodetection Technology Based on Laser Coding Emission

2011 ◽  
Vol 189-193 ◽  
pp. 3745-3749 ◽  
Author(s):  
Jing Guo ◽  
He Zhang ◽  
Xiang Jin Zhang ◽  
Xiao Feng Wang
Keyword(s):  
High Sensitivity ◽  
Avalanche Photodiode ◽  
High Gain ◽  
Low Noise ◽  
High Signal ◽  
Weak Signal ◽  
Echo Signal ◽  
Long Distance ◽  
The Poor ◽  
Theory And Experiment

For the extremely weak echo signal and the poor anti-interference ability of the long-distance laser fuze, the high signal noise ratio (SNR) receiving system based on laser coding mode was designed. In order to improve the weak signal receiving ability, the avalanche photodiode (APD) with high sensitivity, low noise and high gain was adopted. And the optimum multiplication factor of APD when the system obtains the highest SNR was analyzed and calculated. Then, the amplifying circuit optimum matching with APD and the decoding circuit were designed, and validated by the experiments. The theory and experiment results indicate that the design is efficiency and capable to the long distance laser fuze, the system can exactly decode the weak laser coding signals received and export the ignition signal.

Design of Amplifying Circuit for Receiving Weak Signal for Laser Fuze

2013 ◽  
Vol 300-301 ◽  
pp. 1012-1017
Author(s):  
Bing Ting Zha ◽  
He Zhang ◽  
Jun Hong Wang ◽  
Jing Guo
Keyword(s):  
Small Volume ◽  
Avalanche Photodiode ◽  
High Gain ◽  
Low Noise ◽  
Weak Signal ◽  
Echo Signal ◽  
Long Distance ◽  
Detection Range ◽  
Simulation And Experiment ◽  
Processing Circuit

The echo signal received by laser fuze was very weak when the detection range increased. In order to expand the operating range of fuze, the reception capacity of fuze for weak signal should be improved. According to the requirements of long-range laser fuze receiving system as small volume, low-power, low-noise, high-gain, the amplifying circuit of the receiving system was analyzed and designed. To improve the ability of laser fuze for detecting weak signal, the high-sensitive, low-noise, inner-gain avalanche photodiode (APD) was used as a photodetector in the system, and the low-noise preamplifier and voltage amplifying circuit was designed. The noise and frequency response of the amplifying circuit was researched and analyzed by simulation and experiment. The results show that the design is effective and feasible, which can meet the requirements of processing circuit as receiving weak signal from long-distance.

Evidence for Long-range Hydrogen Motion in a-Si:H under Room-temperature Illumination Using Raman Scattering of Amorphous Tungsten Oxide Overlayer

2001 ◽  
Vol 664 ◽  
Author(s):  
Hyeonsik M. Cheong ◽  
Se-Hee Lee ◽  
Brent Nelson ◽  
Angelo Mascarenhas ◽  
Sayten K. Deb
Keyword(s):  
Raman Spectrum ◽  
Tungsten Oxide ◽  
Long Range ◽  
Room Temperature ◽  
Hydrogen Diffusion ◽  
High Sensitivity ◽  
Raman Signal ◽  
Hydrogen Atoms ◽  
Long Distance ◽  
Staebler Wronski Effect

ABSTRACTWe demonstrate that one can detect minuscule amounts of hydrogen diffusion out of a-Si:H under illumination at room temperature, by monitoring the changes in the Raman spectrum of amorphous tungsten oxide as a function of illumination. The Staebler-Wronski effect, the light-induce creation of metastable defects in hydrogenated amorphous silicon (a-Si:H), has been one of the major problems that has limited the performance of such devices as solar cells. Recently, Branz suggested the hydrogen collision model that can explain many aspects of the Staebler-Wronski effect. One of the main predictions of this model is that the photogenerated mobile hydrogen atoms can move a long distance at room temperature. However, light-induced hydrogen motion in a-Si:H has not been experimentally observed at room temperature. We utilized the high sensitivity of the Raman spectrum of electrochromic a-WO3 to hydrogen insertion to probe the long-range motion of hydrogen at room temperature. We deposited a thin (200 nm) layer of a-WO3 on top of a-Si:H, and under illumination, a change in the Raman spectrum was detected. By comparing the Raman signal changes with those for control experiments where hydrogen is electrochemically inserted into a-WO3, we can estimate semiquantitatively the amount of hydrogen that diffuses out of the a-Si:H layer.

A Method of Receiver Circuit in High-Duplicate Pulse Lased Range Finding’s Design and Analysis

2013 ◽  
Vol 631-632 ◽  
pp. 1051-1054
Author(s):  
Zhang Le ◽  
Zhi Yong An ◽  
Yong Ping Hao ◽  
Qin Dai ◽  
Ye Qiu Li
Keyword(s):  
High Speed ◽  
Dynamic Range ◽  
Pulsed Laser ◽  
Pulse Signal ◽  
Laser Ranging ◽  
Echo Signal ◽  
Voltage Comparator ◽  
Range Finding ◽  
Signal Error ◽  
Finding Method

In this paper, the two main reasons are introduced such as great varying range of echo signal power and pulse signal error, which affect the pulse laser ranging accuracy and analyzed on the base of the pulsed laser range finding method. For them, the methods are provided that the AGC technology in the receiving circuit is adopt to extend the dynamic range of the receiver, and gain the high precision receiving pulse signal by using high-speed voltage comparator. Then the problems of great varying range of echo signals caused by different measuring distance and contacting the timing circuit are resolved efficiently.

scholarly journals Genetic Change Within Populations of Phytophthora infestans in the United States and Canada During 1994 to 1996: Role of Migration and Recombination

1998 ◽  
Vol 88 (9) ◽  
pp. 939-949 ◽  
Author(s):  
Stephen B. Goodwin ◽  
Christine D. Smart ◽  
Robert W. Sandrock ◽  
Kenneth L. Deahl ◽  
Zamir K. Punja ◽  
...  
Keyword(s):  
United States ◽  
Sexual Reproduction ◽  
Phytophthora Infestans ◽  
High Sensitivity ◽  
The United States ◽  
Rapid Identification ◽  
Mating Types ◽  
Long Distance ◽  
New Genotype ◽  
The Us

Dramatic changes occurred within populations of Phytophthora infestans in the United States and Canada from 1994 through 1996. Occurrence of the US-8 genotype, detected rarely during 1992 and 1993, increased rapidly and predominated in most regions during 1994 through 1996. US-7, which infected both potato and tomato and made up almost 50% of the sample during 1993, was detected only rarely among 330 isolates from the United States analyzed during 1994. It was not detected at all in more limited samples from 1996. Thus, ability to infect both potato and tomato apparently did not increase the fitness of this genotype relative to US-8, as predicted previously. US-1, the previously dominant genotype throughout the United States and Canada, made up 8% or less of the samples analyzed during 1994 through 1996. A few additional genotypes were detected, which could indicate the beginnings of sexual reproduction of P. infestans within the United States and Canada. However, clonal reproduction still predominated in all locations sampled; opportunities for sexual reproduction probably were limited, because the A1 and A2 mating types usually were separated geographically. The high sensitivity of the US-1 genotype to the fungicide metalaxyl also could have reduced opportunities for contact between the mating types in fields where this compound was applied. The previous correlation between metalaxyl sensitivity and genotype was confirmed and extended to a new genotype, US-17: all US-1 isolates tested were sensitive; all isolates of the US-7, US-8, and US-17 genotypes tested to date have been resistant. Isolates of P. capsici and P. erythroseptica, two other species often found on tomato and potato, could be easily distinguished from each other and from P. infestans using a simple allozyme assay for the enzyme glucose-6-phosphate isomerase. This technique could be useful for rapid identification of species, in addition to genotype of P. infestans. It generally was not possible to predict which genotypes would be present in a location from 1 year to the next. Long-distance movement of US-8 in seed tubers was documented, and this was probably the primary means for the rapid spread of this genotype from 1993 through 1996.

Long-Distance Laser Ranging Lidar Based on Photon Counting Technology

2016 ◽  
Vol 43 (5) ◽  
pp. 0514001
Author(s):  
罗远 Luo Yuan ◽  
贺岩 He Yan ◽  
耿立明 Geng Liming ◽  
王明建 Wang Mingjian ◽  
雷琳君 Lei Linjun ◽  
...  
Keyword(s):  
Photon Counting ◽  
Laser Ranging ◽  
Long Distance

Detection ability of laser ranging system based on multi-telescopes to receive echo signal

2018 ◽  
Vol 47 (9) ◽  
pp. 906002
Author(s):  
张海峰 Zhang Haifeng ◽  
龙明亮 Long Mingliang ◽  
邓华荣 Deng Huarong ◽  
程志恩 Cheng Zhien ◽  
张忠萍 Zhang Zhongping
Keyword(s):  
Laser Ranging ◽  
Echo Signal ◽  
Detection Ability ◽  
To Receive

Research on Laser Ranging Technology Based on Pseudo-Random Code Phase Modulation and Coherent Detection

2018 ◽  
Vol 55 (5) ◽  
pp. 052801
Author(s):  
邱子胜 Qiu Zisheng ◽  
杨馥 Yang Fu ◽  
叶星辰 Ye Xingchen ◽  
李姝欣 Li Shuxin
Keyword(s):  
Phase Modulation ◽  
Coherent Detection ◽  
Laser Ranging ◽  
Random Code
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