Research on Monocular Depth Sensing Method Based on Liquid Zoom Imaging

Round 1

Reviewer 1 Report

This paper primarily investigates a monocular depth perception method based on liquid zoom imaging, presents a well-structured dynamic focus model for a liquid varifocal imaging system, and validates its accuracy and generalization performance through experiments. I think this paper could be published after minor modifications listed as follows:

(1) In section 2, it is recommended that a detailed description of how autofocus is achieved be provided.

(2) The image in Section 3.2 should be revised because image and its caption do not match.

(3) In section 3.4, the authors conducted depth measurements on two different fields of view. It is suggested to highlight the performance of the proposed method in terms of measurement accuracy and efficiency under different fields of view in the discussion section.

(4) In section 3.4, it would be intriguing to investigate how the imaging accuracy and efficiency would be affected if the object to be tested is placed at a tilt or if an irregular geometry is used, it is recommended to provide depth measurement results for different target shapes.

(5) In section 4, it is better for the authors to summarize the main contributions of the entire paper and discuss the advantages and limitations of the proposed approach. 

The manuscript is generally well written, and the English level of the article is acceptable. The authors have managed to present their research in a mostly clear manner, and the language used is generally concise, though there are moments where it lacks coherence. While the paper is mostly readable, there are some issues that could be polished to enhance clarity and understanding.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

After studying the manuscript, there are the following questions.

1. Has zoom been considered with moving the lenses f'=const to change the magnification?

2. Is chromatic aberration important in an optical system for the micro robot?

3. Have any studies been carried out on changing the position of the main planes of a liquid lens when its optical power changes?

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

In this work, the authors present a monocular depth sensing method based on flexible zoom imaging by combining liquid zoom mechanism with visual measurement technology. they built a physical platform for liquid monocular visual measurement system based on the designed system configuration and working mechanism. For targets of different shapes, the system can achieve high depth measurement accuracy (depth measurement error for the experimental types of targets was less than 5.98%). The innovation and potential applications of the proposed method are commendable. However, there are still some questions that require improvement and clarification:

1.     The aperture size of the imaging system affects the depth of field. If the aperture of the imaging system is small and the spatial point is in a different location but all are within the depth of field, will this affect the accuracy of the depth measurement?

2.     According to Table 3, the Measure relative error of Group number 3 is 7.05%, which is the highest value. An explanation for this discrepancy is requested from the authors.

3.     It is recommended to avoid duplicating the same form on multiple pages.

Overall, this manuscript is generally well-written. However, it requires major revisions before publication.

The language quality of English is not recommended

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

The authors have explained four main problems in the revised manuscript according to our comments. Now, it has enough technical details and discussions to support its publication on Photonics.