Fiber Coupled High Power Nd:YAG Laser for Nondestructive Laser Cleaning

Round 1

Reviewer 1 Report

This manuscript presents a design on a fiber coupled high power side-pumped Nd: YAG laser system for laser cleaning. I find this paper not suitable for publication.

1)Figure 1(b) is too smaller, and it should correspond to each component in Figure a one by one;

2) The section of 3 "Theoretical analysis", the theoretical analysis process and the source of Figure 2 should be provided;

3)Page 4, Line 128: "electro-optical conversion efficiency", how is this efficiency obtained?

4)How was Figure 4 obtained?

5)The format of Tables 1 and 2 is not standardized;

6)Please add the scale bar for the left image in Figure 7.

The English grammar should be checked again. 

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

This paper presents a high power Q-switched Nd:YAG laser system for nondestructive laser cleaning of thermal control coatings. The paper compares the laser cleaning effect of the Nd:YAG laser with a commercial fiber laser and shows that the Nd:YAG laser has better performance in terms of substrate damage and surface roughness. The article is well-written but it also has some concerns that need to be addressed before publication.

1. The authors does not provided a detailed comparison or discussion of Nd:YAG laser system with other relevant works in the field of Nd:YAG lasers for laser cleaning applications. The novelty and competitiveness of the proposed high-power laser for cleaning are not clear compared to other Nd:YAG lasers.?

2. In fact, excessively peak power intensity affects the coating removal rate, quality, and substrate damage adversely, so why higher power laser source is needed for cleaning? The authors need to show evidence that higher power makes cleaning more effective and measure the efficiency of coating removal with low substrate damage.

3. The paper lacks a comprehensive and systematic evaluation of the laser cleaning effect of the Nd:YAG laser and the fiber laser. The authors should perform statistical analysis to evaluate the Nd:YAG laser and the fiber laser in terms of coating removal rate, depth, area, substrate damage, surface roughness, residual coating particles, etc.

4. The sample image (Fig 7a-c, 8) is too small and unclear to draw reliable conclusions.

5. In line 57, the sentence “Thermal control coating is wildly used in spacecrafts to withstand huge temperature range under the rigorous space environment to keep stable working condition of precise instruments.”  Do you mean‘widely’ instead of ‘wildly’?

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

In this paper, the authors propose a prototype laser machine (a fiber-coupled, side-pumped, high-power Nd:YAG laser system) for nondestructive removal of thermally controlled coatings. The introduction is well written and consistent with the results presented. The results and discussion chapter is well organized and the results are clearly described.

 

I propose the acceptance of the work with minor changes.

 

1. check of references, (references 5, 6, 11...)

2. I suggest revising the English

 

I suggest revising the English, for example:

Page 1, line 10

In this study, a fiber coupled high power side-pumped Nd:YAG laser system designed for laser cleaning application is demonstrated. 

May be better: 

In this study, a fiber coupled high power side-pumped Nd:YAG laser system for laser cleaning is presented. 

Page 1, line 24

Laser cleaning technique has been developed rapidly in recent years [1, 8, 11, 23]. 

May be better:

Laser cleaning technology has developed rapidly in recent years [1, 8, 11, 23].

Page 1, line 25

Compared with chemical, mechanical grinding and ultrasonic cleaning method, laser cleaning technology is an environmental-friendly process possessing merits of high efficiency, good stability and slight damage to the substrate [23].

May be better: 

 

Compared with chemical, mechanical grinding, and ultrasonic cleaning methods, laser cleaning technology is an environmentally friendly method, which is characterized by high efficiency, good stability, and little damage to the substrate [23].

 

Page 2 line 52

However, an unstable zone exists, which leads to a small variation range of laser output power. 

May be better:

However, there is an unstable zone that leads to a small variation in laser output power.

Page 2, line 68

But the fiber coupling efficiency is not stable and varies with pump current due to the low-order aberration defocus of the MOPA system. 

May be better:

However, the fiber coupling efficiency is not stable and varies with pump current due to defocusing of the MOPA system by low-order aberration.

Page 2, line 66

In this paper, a high power pulsed laser source for laser cleaning application have been obtained from a LD side-pumped Nd:YAG AO Q-switched laser. 

May be better:

In this work, a high-power pulsed laser source for laser cleaning applications was obtained from a LD side-pumped Nd: YAG AO Q-switched laser. 

 

Page 9, line 266

In conclusion, a high power, AO Q-switched Nd:YAG MOPA laser system for laser cleaning has been demonstrated. 

May be better:

Here the AO Q-switched Nd: YAG MOPA laser system with high power for laser cleaning was presented.

 

Page 9, line 273

The laser head prototype model consisting of laser oscillator and first stage amplifier was developed and installed into a laser cleaning equipment for nondestructive cleaning of thermal control coatings of areospacecrafts.

May be better: 

The prototype laser head, consisting of a laser oscillator and first stage amplifier, was developed and incorporated into a laser cleaning system for nondestructive cleaning of spacecraft thermal control coatings.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The author has completely revised it according to my comment.