Underwater distance measurement using frequency comb laser

Zhai, Xiaoyu; Meng, Zhaopeng; Zhang, Haoyun; Xu, Xinyang; Qian, Zhiwen; Xue, Bin; Wu, Hanzhong

doi:10.1364/oe.27.006757

Cited by 9 publications

(4 citation statements)

References 38 publications

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“…Researchers have thus ventured into various methodologies for underwater stereo matching, employing specialized camera systems engineered to function effectively in these challenging conditions. For instance, Zhai et al proposed an underwater ranging method based on the frequency comb laser [15]. Additionally, the adaptation of stereo matching algorithms has emerged as a vital strategy for addressing issues like light attenuation and limited visibility, ultimately bolstering the robustness and reliability of underwater stereovision.…”

Section: Stereo Matching Methodsmentioning

confidence: 99%

Advanced Underwater Measurement System for ROVs: Integrating Sonar and Stereo Vision for Enhanced Subsea Infrastructure Maintenance

Zhang,

Han,

Han

et al. 2024

JMSE

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In the realm of ocean engineering and maintenance of subsea structures, accurate underwater distance quantification plays a crucial role. However, the precision of such measurements is often compromised in underwater environments due to backward scattering and feature degradation, adversely affecting the accuracy of visual techniques. Addressing this challenge, our study introduces a groundbreaking method for underwater object measurement, innovatively combining image sonar with stereo vision. This approach aims to supplement the gaps in underwater visual feature detection with sonar data while leveraging the distance information from sonar for enhanced visual matching. Our methodology seamlessly integrates sonar data into the Semi-Global Block Matching (SGBM) algorithm used in stereo vision. This integration involves introducing a novel sonar-based cost term and refining the cost aggregation process, thereby both elevating the precision in depth estimations and enriching the texture details within the depth maps. This represents a substantial enhancement over existing methodologies, particularly in the texture augmentation of depth maps tailored for subaquatic environments. Through extensive comparative analyses, our approach demonstrates a substantial reduction in measurement errors by 1.6%, showing significant promise in challenging underwater scenarios. The adaptability and accuracy of our algorithm in generating detailed depth maps make it particularly relevant for underwater infrastructure maintenance, exploration, and inspection.

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Section: Stereo Matching Methodsmentioning

confidence: 99%

Advanced Underwater Measurement System for ROVs: Integrating Sonar and Stereo Vision for Enhanced Subsea Infrastructure Maintenance

Zhang,

Han,

Han

et al. 2024

JMSE

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show abstract

“…However, in sharp contrast to the success in air, frequency combs have rarely been exploited underwater. In our previous work [48], we have made attempts to measure underwater distances using green frequency combs, with consideration of the optical transmission window (480-530) nm in water. In both the time and frequency domains, we successfully measure the underwater distances up to 8 m with about 100 μm uncertainty, and the Harvey formula used to correct the water refractive index makes the dominating contribution to the combined uncertainty.…”

Section: Introductionmentioning

confidence: 99%

Precise underwater distance measurement using laser frequency comb

Xu¹,

Zhao²,

Zhang³

et al. 2021

Metrologia

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Underwater distance measurement has been playing an important role in the fields of underwater navigation, search and rescue, and bathymetric survey. However, limited by the measurement sources (e.g. acoustic pulses or incoherent optical pulses), the precision can only achieve centimeter level at best, which greatly obstructs the advancement of underwater science and technology. Recent developments of optical frequency combs have given rise to revolutionary progress in metrology, spectroscopy, and optical distance measurement in air. However, frequency comb-based underwater distance measurement has rarely been reported. In this work, we describe a spectral interferometry-based method using a laser frequency comb at 518 nm (green light), which is capable of underwater distance measurement with high precision and accuracy. Due to the inherently dispersive characteristic of water, the measurement pulse will be chirped, and the spectrograms exhibit unstable oscillations, the spectral phase of which features a quadratic law. Distances up to 4.4 m and displacements down to 5 μm underwater can be determined by virtue of the spectral phases. The experimental results show the differences within ±4 μm at 4.4 m range, compared to the reference values. The Allan deviation is 1.596 μm at 5 s averaging time, 481 nm at 100 s averaging time, and can achieve 261 nm with 540 s averaging time. Our work could provide a promising and powerful tool for underwater distance measurement with high precision at long range, and open the door to a host of underwater applications related to the measurement of distance, e.g. mapping and positioning.

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“…Underwater distance measurement has been playing significant role in marine science and technology (e.g., in fields of ocean sounding, underwater positioning, and navigation), which mainly relies on the time‐of‐flight scheme utilizing the acoustic pulses as mentioned before. Recently, our group used an optical frequency comb at 518 nm (green light) to determine distances underwater, and showed that the measurement uncertainty can reach the micrometer level (10 −5 in relative, limited by the uncertainty of the Harvey formula) . Despite this, the working distance of the optical frequency comb is limited by the strong attenuation that occurs when optical waves travel in water.…”

Section: Introductionmentioning

confidence: 99%

Precise Underwater Distance Measurement by Dual Acoustic Frequency Combs

Qian

Zhang

et al. 2019

Annalen der Physik

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Underwater acoustics is of fundamental importance for marine science and technology. However, acoustic waves transmitted by state‐of‐the‐art underwater acoustic systems are not inherently phase locked, which hinders the development of underwater acoustic technology. For example, the precision of underwater distance measurement can only achieve centimeter level. As a versatile tool, optical frequency combs have enabled revolutionary progress in optical metrology and precision measurement. In parallel with optical frequency combs, here, the generation of fully stabilized, underwater acoustic frequency combs is reported, in which equidistant acoustic modes are produced via a hydroacoustic transducer. The precision of each individual acoustic mode is measured to be 10−9 at 1 s and 10−12 at 1000 s averaging times. Underwater distance measurements are carried out in an anechoic pool using a dual‐comb scheme. Comparison with reference values shows consistency within 50 µm (7 × 10−6 in relative). The relatively long‐duration experiments at 7 m distance yield an Allan deviation of 1.8 µm (2.6 × 10−7 in relative) at 1 s and further 480 nm (6.8 × 10−8 in relative) at 40 s averaging times. The approach to acoustic frequency comb generation offers a promising and powerful platform for future underwater distance measurement, positioning, and navigation.

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Underwater distance measurement using frequency comb laser

Cited by 9 publications

References 38 publications

Advanced Underwater Measurement System for ROVs: Integrating Sonar and Stereo Vision for Enhanced Subsea Infrastructure Maintenance

Advanced Underwater Measurement System for ROVs: Integrating Sonar and Stereo Vision for Enhanced Subsea Infrastructure Maintenance

Precise underwater distance measurement using laser frequency comb

Precise Underwater Distance Measurement by Dual Acoustic Frequency Combs

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