Digital Shearography for NDT: Phase Measurement Technique and Recent Developments

Round  1

Reviewer 1 Report

The authors give a good review on the state of the art of shearography and its application to non-destructive testing of composite materials. The reviewer did not detect any flaw as far as the content is concenred. There are however several minor typographical and english errors that can be corrected in the proof reading process. I recommend to accept this manuscript. 

Author Response

Response to Reviewer 1 Comments

Point 1: The authors give a good review on the state of the art of shearography and its application to non-destructive testing of composite materials. The reviewer did not detect any flaw as far as the content is concenred. There are however several minor typographical and english errors that can be corrected in the proof reading process. I recommend to accept this manuscript.

Response 1: Thank you for the positive comment, typographical and english errors have been checked carefully in the revised manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors propose a review of the digital shearography techniques for NDT of composite materials. The paper presents an interesting summary of the technique, however there are several issues that need to be clarified and some other addressed carefully. Therefore, major modifications of the paper are suggested, together with a review of the English language.

I summarize my suggested revisions below.

 Abstract

 The abstract is well done, while it is not clear in line 20 the meaning of “..relative insensitivity to environmental interruption…” Please clarify.

1.   Introduction.

 The introductory part needs a review, starting from the definition of internal defects in composite materials which is too general and vague. The word “disband” should become “disbond”, but it is still not correct while referring to delaminations. Indeed, a disbond is generally referred to external bonding, such as adhesives, and not internal delaminations.

Again, in line 37, the “integrity of composite materials” is a rough definition. Please add more details.

The references in the discussion are often a simple list. It would have been more useful to increase their details and usefulness to the paper, together with reducing their number (ex: line 41 “[3-9]”)

In several parts of the paper is defined the “…relative insensitivity to environmental interruptions..”, as in line 20, 45, 111 etc. This is a no meaning sentence: relative is not a technical word, and I don’t understand the meaning of “interruption”. Maybe is it a “disturbance”?

Again, in line 51, why an environmental disturbance is not affecting the results? Of course a rigid body motion is not producing strain, but what’s about for example a variation of temperature? In my opinion all the “environmental” effect should be reconsidered and reviewed.

2. Digital Shearography

 Many points need to be clarified in this paragraph. The overall setup is barely described, with no mentioning of the actual setup of the cameras and their resolution. Is there any influence of any parameter on the results (ex. External temperature, etc..)? How the setup of the apparatus has been performed? A calibration sample must been used? Please clarify.

In line 77 the “..modified Michelson interferometer…” is mentioned without any indication in the figure.

The description of the light waves behaviour is well known, such as the equations. A reference could be used for those.

Line 97. “…appear on the shearogram when.” ? something is missing.

Line 111. See before

Line 118. The holographic NDT is introduced. References?

3.  Phase measurement technique

Line 138: please explain why the real time subtraction has a 10 times higher sensitivity? Are the authors talking about the accuracy?

In the temporal phase shift technique is stated that (line 160) “ …using four equations is fast and simple …etc…” . Please clarify.

Eqn 8 please check the I₄ eqn.

Line 183: The 4+2 algorithm phase map quality is better. Meaning of “quality” and “better”?

The following review of the carrier frequency method is well done. In line 235 the literature is cited in a different way than before, by adding the name of the first author and the year (Pedrini in 1996). Please align with the rest of the paper.

4.     Recent development

 Line 328. Is a repetition of previous sentences.

Author Response

Thank you for your fruitful comments. In the attach file, we have answered the comments carefully and addressed all the changes and revisions one by one.

Author Response File: Author Response.pdf

Reviewer 3 Report

Please find the attach file for reviewer comments

Comments for author File: Comments.pdf

Author Response

Thank you for your fruitful comments. In the attach file, we have answered the comments carefully and addressed all the changes and revisions one by one.

Author Response File: Author Response.pdf

Round  2

Reviewer 3 Report

Authors made extensive changes to the manuscript. I recommend this manuscript to publish in Applied Science. Thanks