Coaxial LiDAR System Utilizing a Double-Clad Fiber Receiver

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper presents a coaxial LiDAR system using a double-clad fiber receiver, where the single-mode core emits the laser and the multimode inner cladding collects the return signal. The approach effectively removes near-field blind zones and improves collection efficiency compared with conventional circulator-based designs. The work is clearly written, the experimental data support the conclusions, and the topic fits well within Photonics. I find the DCF-based configuration compact, stable, and easy to align. However, the authors should better clarify the novelty compared with other recent coaxial or DCF LiDAR systems, briefly discuss possible limitations such as coupling loss or long-range performance, and slightly improve figure readability. Overall, the paper is technically sound and can be accepted after minor revision.

Author Response

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Reviewer 2 Report

Comments and Suggestions for Authors

1)  As a coaxial optical system, please provide additional analysis and solutions to the impact of internal reflections.

2)  As the author notes, there have been numerous previous designs for coaxial lidar or active imaging systems. Please provide a quantitative comparative analysis. For example, as a fiber-based coaxial optical system, do these systems offer significant advantages over fiber circulator- based lidar system in terms of laser transmission efficiency, reception efficiency, and crosstalk? A quantitative comparative analysis should be conducted.

Author Response

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Reviewer 3 Report

Comments and Suggestions for Authors

This paper presents an innovative and promising design for a coaxial Time-of-Flight (ToF) LiDAR system utilizing a Double-Clad Fiber (DCF) receiver. This approach is highly commendable as it inherently achieves coaxial beam alignment while effectively mitigating optical crosstalk between the transmitting core and the receiving cladding. The demonstrated enhancement in echo power collection is significant. The authors are encouraged to address the following points for improved clarity and validation.
1.  The manuscript currently provides only schematic diagrams (Figure 2) of the system architecture. To enhance the clarity and practical understanding of the implementation, it is strongly recommended that the authors supplement the text with photographs of the actual experimental setup or the integrated device apparatus.
2. The setup includes a Galvanometer Scanner (GS) pair (Figure 2a), which suggests the system is intended for 3D scanning applications. However, the paper does not present any real-world 3D point cloud images. Please clarify the system's full scanning capability and, if possible, provide real-scene 3D point cloud data.
3. A significant advantage of coaxial LiDAR systems, and a key claim of this paper (e.g., "eliminating blind spots," Abstract, line 18), is the reduction or elimination of the near-field blind zone typical in non-coaxial setups. While the text discusses this concept and references Table 1 (which compares off-axis displacement in non-coaxial systems), the paper does not explicitly quantify or present the practical near-field performance of the proposed DCF system. Please state the closest minimum measurable distance (blind zone) achieved by the DCF system and provide corresponding experimental data or a dedicated figure illustrating the system's performance at very short ranges.
4. In the definition of the ranging formula (Equation 1), the preceding notation "a=1" is unclear and appears mathematically insignificant for the final calculation of R. Please either remove this superfluous parameter or explicitly define its physical or mathematical meaning within the context of the distance calculation.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

My questions have been responed to.   However, I think maybe an additional comparative analysis of DCF-based and circulator-based methods would be more illustrative, rather than simply analyzing the advantages of the method based on the performance parameters of each device(DCF or SMF/MMF circulator).

Author Response

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Author Response File: Author Response.pdf