Stepped Confocal Microlens Array Fabricated by Femtosecond Laser

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript combines fs laser processing and chemical etching to produce confocal microlens array molds with different focal lengths on the stepped fused silica surface. A stepped confocal microlens array is manufactured by the polydimethylsiloxane molding method, which can realize the functions of obtaining multiple depths of field, multi - scale field of view and multi - resolution images on the confocal surface. It also studies the influence of laser focusing position, pulse number, pulse energy, wet etching time on the optical performance of microlenses. Although this is a novel and worth studying method, minor revisions are required.

 

1.The experiment should provide the pulse width, repetition rate, pulse - to - pulse stability, focal spot diameter and focal depth of the fs laser used for processing the fused silica glass.

2.The dimensions (such as length, width, and thickness) of the prepared material, along with the model of the CO₂ laser and its processing parameters for fabricating the stepped fused silica material, should be provided.

3.It is necessary to provide reference literature regarding the interaction mechanism between the fs laser and the fused silica glass.

4.What is the size of the microlens array in the simulation presented in Fig. 8?

5.What are the HF etching concentrations and etching times for the HMLA and LMLA with different focal lengths prepared as shown in Fig. 10?

Author Response

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Reviewer 2 Report

Comments and Suggestions for Authors

The study presents a novel approach to fabricating stepped confocal microlens arrays with significant potential for applications in multi-depth imaging and compact optical systems. While the methodology and experimental validation are well-structured, there are still some aspects that need to be improved. Therefore, a minor revise is required. Addressing minor inconsistencies in parameter reporting and clarifying technical rationales would further enhance the manuscript's rigor and reproducibility.

 

1.Figure 5(g) is labeled but not discussed in the text (Section 3.1). Clarify its purpose or correct the figure numbering.

2.Fluctuations in focal length with focus position lack explanation. Briefly discuss possible causes.

3.Minor grammatical errors exist. Examples: “The averaged values” → “The average values”; ambiguous phrases like “outer boundary points of the envelope” need rephrasing.

4.Step height definition is unclear. Specify how the 25 μm step height in Section 3.3 was measured.

5.Figure 10a–f references are inconsistent. Ensure all subfigures are explicitly mentioned in the text.

6.Etching time ranges lack justification. Explain why etching durations were set to 3–8 hours (Section 3.1).

7.Simulation wavelength mismatch: The simulation uses 500 nm light (Section 3.2), but the experimental setup employs a white light source.

Comments on the Quality of English Language

None

Author Response

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Reviewer 3 Report

Comments and Suggestions for Authors

This study presents a stepped confocal microlens array (SCMLA) fabricated via femtosecond laser and chemical etching, achieving multi-focal confocal imaging by tuning microlens curvature on a stepped substrate. The experiments systematically investigate the influence of laser parameters (focus position, pulse number, energy) and etching time on microlens morphology (diameter, depth, focal length).

While the research is comprehensive, revisions are recommended prior to acceptance: 

Revision Suggestions: 

1. The current parameter analysis relies on single-variable empirical correlations. It is critical to extract generalized laws (e.g., etching rate equations, energy-morphology correlation formulas) to support process standardization and broaden applicability.
2. Address fluctuating trends in pulse energy effects (e.g., Figure 5e-f) by incorporating error bars, statistical significance tests, or mechanistic explanations.

Author Response

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Author Response File: Author Response.docx