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Frequency modulated continuous wave (FMCW) laser ranging is one of the most interesting techniques for precision distance metrology. It is a promising candidate for absolute distance measurement at large standoff distances (10 to 100 m) with high precision and accuracy, and no cooperation target is needed during the measuring process. How to improve the measurement resolution in practice has been the research focus of the FMCW laser ranging in recent years.FMCW laser ranging system uses the method which may convert the measurement of flight time to the frequency measurement, while the ranging resolution can be determined by the tuning range of the optical frequency sweep in theory. The main impact-factor that reduces the resolution is the tuning nonlinearity of the laser source, which may cause an amount of error points within the sampling signal. So a dual-interferometric FMCW laser ranging system is adopted in this paper. Compared to the traditional Michelson scheme, an assistant interferometer is added. The assistant interferometer has an all-fiber optical Mach-Zehnder configuration, and the delay distance is at least 2 times longer than OPD (optical path difference) of the main interferometer. Because it provides the reference length, the length of the fiber must remain unchanged. The interference signal is obtained on the photodetector. At the time points of every peak and bottom of the auxiliary interferometer signal, the beating signal from the main interferometer is re-sampled. The original signal is not the equal time intervals, while the re-sampled signal is the equal optical frequency intervals. Based on the property of the re-sampled signal, a method by splicing the re-sampled signal to optimize the signal processing is proposed, by which the tuning range of the laser source limitation can be broken and high precision can be easily obtained. Also, a simple high-speed measuring method is proposed.Based on all the above principles, the two-fiber optical frequency-modulated continuous wave laser ranging system is designed. The delay fiber in the FMCW laser ranging system is 40.8 m long, and the tuning speed and tuning range of the laser source are set to 10 nm/s and 40 nm respectively. Experiments show that the optimization method can effectively improve the measurement resolution and measuring efficiency; in the 26 measuring ranges, 50 m resolution can be easily obtained and the error is less than 100 m.
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Keywords:
- FMCW /
- the absolute distance measurement /
- interferometry
[1] Liu Z X, Zhu J G, Yang L H, Liu H Q, Wu J, Xue B 2013 Meas. Sci. Technol. 24 105004
[2] Wu H, Zhang F, Cao S, Xing S, Qu X 2014 Opt. Express 22 10380
[3] Liao S S, Yang T, Dong J J 2014 Chin. Phys. B 23 073201
[4] Wu H, Zhang F, Li J, Cao S, Meng X, Qu X 2015 Appl. Opt. 54 5581
[5] Roos P A, Reibel R R, Berg T, Kaylor B, Barber Z W, Babbitt W R 2009 Opt. Lett. 34 3692
[6] Wang G C, Yan S H, Yang J, Lin C B, Yang D X, Zou P F 2013 Acta Phys. Sin. 62 070601 (in Chinese) [王国超, 颜树华, 杨俊, 林存宝, 杨东兴, 邹鹏飞 2013 62 070601]
[7] Cabral A, Rebordão J 2007 Opt. Engineering. 46 073602
[8] Li Z D, Jiang Y S, Snag F, Wnag L C, Deng S G, Xin Y, Guo J P 2011 Acta Optica Sinica 31 0314001 (in Chinese) [李志栋, 江月松, 桑 峰, 王林春, 邓士光, 辛 遥, 郭泾平 2011 光学学报 31 0314001]
[9] Roos P A, Reibel R R, Berg T, Kaylor B, Barber Z W, Babbitt W R 2010 Opt. Lett. 34 3692
[10] Satyan N, Vasilyev A, Rakuljic G, Leyva V, Yariv A 2009 Opt. Express 17 15991
[11] Iiyama K, Matsui S, Kobayashi T, Maruyama T 2011 IEEE Photonics Technol. Lett. 23 703
[12] Baumann E, Giorgetta F R, Coddington I, Sinclair L C, Knabe K, Swann W C, Newbury N R 2013 Opt. Lett. 38 2026
[13] Shi G, Zhang F M, Qu X H, Meng X S 2014 Acta Phys. Sin. 63 184209 (in Chinese) [时光, 张福民, 曲兴华, 孟祥松 2014 63 184209]
[14] Shi G, Zhang F, Qu X, Meng X 2014 Opt. Engineering 53 122402
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[1] Liu Z X, Zhu J G, Yang L H, Liu H Q, Wu J, Xue B 2013 Meas. Sci. Technol. 24 105004
[2] Wu H, Zhang F, Cao S, Xing S, Qu X 2014 Opt. Express 22 10380
[3] Liao S S, Yang T, Dong J J 2014 Chin. Phys. B 23 073201
[4] Wu H, Zhang F, Li J, Cao S, Meng X, Qu X 2015 Appl. Opt. 54 5581
[5] Roos P A, Reibel R R, Berg T, Kaylor B, Barber Z W, Babbitt W R 2009 Opt. Lett. 34 3692
[6] Wang G C, Yan S H, Yang J, Lin C B, Yang D X, Zou P F 2013 Acta Phys. Sin. 62 070601 (in Chinese) [王国超, 颜树华, 杨俊, 林存宝, 杨东兴, 邹鹏飞 2013 62 070601]
[7] Cabral A, Rebordão J 2007 Opt. Engineering. 46 073602
[8] Li Z D, Jiang Y S, Snag F, Wnag L C, Deng S G, Xin Y, Guo J P 2011 Acta Optica Sinica 31 0314001 (in Chinese) [李志栋, 江月松, 桑 峰, 王林春, 邓士光, 辛 遥, 郭泾平 2011 光学学报 31 0314001]
[9] Roos P A, Reibel R R, Berg T, Kaylor B, Barber Z W, Babbitt W R 2010 Opt. Lett. 34 3692
[10] Satyan N, Vasilyev A, Rakuljic G, Leyva V, Yariv A 2009 Opt. Express 17 15991
[11] Iiyama K, Matsui S, Kobayashi T, Maruyama T 2011 IEEE Photonics Technol. Lett. 23 703
[12] Baumann E, Giorgetta F R, Coddington I, Sinclair L C, Knabe K, Swann W C, Newbury N R 2013 Opt. Lett. 38 2026
[13] Shi G, Zhang F M, Qu X H, Meng X S 2014 Acta Phys. Sin. 63 184209 (in Chinese) [时光, 张福民, 曲兴华, 孟祥松 2014 63 184209]
[14] Shi G, Zhang F, Qu X, Meng X 2014 Opt. Engineering 53 122402
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