Improvements of Computational Ghost Imaging by Using Sequenced Speckle

Round 1

Reviewer 1 Report

Dear Editor,

this paper presents an analysis of computational ghost imaging with speckle size varying in different subsequent steps. The results can have some interest for people working in the field. The results looks sound and sufficient to the goal of the work.

I suggest publishing the paper.

Only, as minor remarks, I found fig. 8 a little confuse and I suggest quoting some review papers on quantum imaging.

 

Author Response

Re: Manuscript ID: applsci-2369518 and Title: "Improvements of Computational Ghost Imaging by Using Sequenced Speckle"

Thank you for your letter and the reviewers’ comments concerning our manuscript entitled “applsci-2369518” (ID). Those comments are valuable and very helpful. We have read through the comments carefully and have made corrections. Based on the instructions provided in your letter, we uploaded the file of the revised manuscript. Revisions in the text are shown using red highlight for additions, and strikethrough font for deletions. The responses to the reviewer's comments are marked in red and presented following.

We would love to thank you for allowing us to resubmit a revised copy of the manuscript and we highly appreciate your time and consideration.

Sincerely.

Sukyoon Oh

Reviewer #1:

1. We have revised the text to address your concerns and hope it is clearer. Please take a  see page 6 of the revised manuscript in Figure 8.

Author Response File: Author Response.docx

Reviewer 2 Report

In this paper, a computational ghost imaging (GI) scheme using sequenced random speckle pattern illumination. However, I think that major revisions are required prior to publish this manuscript. To this end, the reviewer has the following comments:

 

1. In the manuscript, the innovation point is not clear and the superiority is not clearly demonstrated compared with other many research study in Section 1.

 

2. The experimental conditions and system parameters are not given, and this is necessary for evaluating the effect of the method.

 

3. The application conditions of the approach are not given, and this is necessary for evaluating the effect of the method.  

 

4. The authors have not provided the references for most of the equations.

 

5. The quality of figure 4 needs to be improved, and the size of font is very small.

 

6. English should be improved. Such as “Furthermore, we based the same model for the TGI to simulate the observed behavior of the SGI in Fig.6 simulation.”.

English should be improved. Such as “Furthermore, we based the same model for the TGI to simulate the observed behavior of the SGI in Fig.6 simulation.”.

Author Response

Re: Manuscript ID: applsci-2369518 and Title: "Improvements of Computational Ghost Imaging by Using Sequenced Speckle"

Thank you for your letter and the reviewers’ comments concerning our manuscript entitled “applsci-2369518” (ID). Those comments are valuable and very helpful. We have read through the comments carefully and have made corrections. Based on the instructions provided in your letter, we uploaded the file of the revised manuscript. Revisions in the text are shown using red highlight for additions, and strikethrough font for deletions. The responses to the reviewer's comments are marked in red and presented following.

We would love to thank you for allowing us to resubmit a revised copy of the manuscript and we highly appreciate your time and consideration.

Sincerely.

Sukyoon Oh

Reviewer #2:

1. We have revised the text to address your concerns and hope it is clearer. Please see page 1 of the abstract.
2. We have added the experimental condition and system parameters. Please take a look at page 2 and section 2.1 lines 1–20.
3. We have added the application conditions. Please take a look at page 2 and section 2.1 lines 14.
4. We have added the Author of the equation. Please take a look at page 3 and section 2.2 lines 15.
5. We have increased the font size and changed the 4. figure. I hope it is a bit clear.
6. We have improved the sentence you pointed out. Please take a look at page 7 line 5.

Author Response File: Author Response.docx

Reviewer 3 Report

In this paper, titled “Improvements of computational ghost imaging by using sequenced speckles”, the authors developed three sequences of speckle patterns and applied each for computational ghost imaging. Termed “different step”, “different directions”, and “different groups”, the authors evaluated the quality of the reconstructed results from each speckle pattern sequence from the contrast to noise ratio and resolution.

            In general, extracting information from hidden and/or opaque structures is of great interest to imaging scientists. However, after reading the manuscript, the reviewer finds it difficult to endorse it for publication in the current format. The novelty and significance of the research does not seem obvious. Theoretical reasonings of why some speckle pattern or sequence works better than others are missing. Descriptions and figures are not well presented. Here are some more detailed comments.

1.      The scope of the work and key accomplishments should be more clearly stated in the Abstract and Introduction. Is the goal of developing a speckle pattern/sequence to increase the computational time without losing quality?

2.      For the system design (Fig.1), what’s the size of the detecting area of the photodiode? Does it record all the forward propagating/scattering light from the object? Why the Fresnel light propagation from the DMD to the object was not considered in the theoretical model? What’s the pitch size of the DMD?

3.      In Section 2.2, the authors mention “N different illuminations of random speckle patterns”, and “N is the total number of iterations”. The authors used the same symbol to denote two quantities. This is misleading. So how many patterns were used in each experiment?

4.      Till Section 2.2, the motivation for developing different speckle patterns is not clearly stated. More importantly, the reasoning and/or a theoretical explanation of why DD, DS, and DG are supposed to work better should be included. A simple numeric simulation is not adequate to convince the audience.

5.      The descriptions of the speckle pattern/sequence design, as well as Figure 3 and Figure 4, should be more coherent and straightforwardly clarified. Especially, the arrangement of Figure 4 is confusing and hard to understand. Other than speckle size and order of the patterns, the number of generated patterns is also a variable in these experiments. How did the authors ensure that the pattern number does not affect the reconstruction quality?  

6. Figure 6 and Figure 7, the simulation and experiment images did not use the same colormap. The CNR/Resolution plots of the simulation and experiment do not have the same scale for the y-axis. DD-2 CNR seems worse than the simulation, and it is not clear why.

 

7.       Since the reviewer does not quite understand the logic, mechanism, and working principle of DG sequences, it is also difficult to appreciate the results of Figure 8. All the denotations and legends are distracting, and hard to follow. 

Author Response

Re: Manuscript ID: applsci-2369518 and Title: "Improvements of Computational Ghost Imaging by Using Sequenced Speckle"

Thank you for your letter and the reviewers’ comments concerning our manuscript entitled “applsci-2369518” (ID). Those comments are valuable and very helpful. We have read through the comments carefully and have made corrections. Based on the instructions provided in your letter, we uploaded the file of the revised manuscript. Revisions in the text are shown using red highlight for additions, and strikethrough font for deletions. The responses to the reviewer's comments are marked in red and presented following.

We would love to thank you for allowing us to resubmit a revised copy of the manuscript and we highly appreciate your time and consideration.

Sincerely.

Sukyoon Oh

Reviewer #3:

1. We have revised the text to address your concerns and ensure clarity. Please refer to the revised manuscript's page 1 in the abstract and page 4, line 3 (Based on the findings from previous pseudo-thermal ghost imaging experiments [19]). Additionally, we have included explicit results on page 10, lines 24-28.
   To briefly summarize, the objective of our experiment was to achieve superior ghost imaging (GI) with enhanced speed compared to the image quality of traditional GI (TGI) using sequential speckle patterns. 
   
   
2. We have revised Figure 1. Actually, we used also a lens behind the object to capture the whole intensity from PD. We considered also the Fraunhofer diffraction value which is z(50cm) > (402um)^2/(632nm).  Our experiments were conducted in the Fraunhofer diffraction range. We have added the pitch information of DMD in section 2.1 line 4.
3. I have figured out your comment. We have deleted the sentence to avoid using double meaning and filled in the exact pattern number. Please take a look at section 2.2 line 8.
4. We have revised the text to address your concerns and hope it is clearer. On page 4 line 3 (Based on the findings from previous pseudo-thermal ghost imaging experiments [19],).
5. We have revised Figure 4 with your comments and hope it is clearer. In order to investigate the effect of the spacing of the number of patterns and the size of the patterns, we divided them into several groups as shown in Figure 4.
6. We have made revisions to Figures 6 and 7, ensuring that the Y-axis is aligned. Unfortunately, we only have the image file and not the original MATLAB file, making it challenging to apply the same colormap. However, we appreciate your valuable feedback, and we will make the necessary adjustments in the upcoming experiment. As depicted in Figures 6, 7, and 8, the CNR values obtained from the actual experiments consistently appear smaller compared to those from the simulations. This discrepancy can be attributed to the non-ideal experimental conditions, where factors such as incomplete noise blocking were present.
7. We have revised Figures 4 and 8 with your comments and hope it is clearer.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

English need to be improved.

English need to be improved. 

Author Response

Dear Reviewer,

In response to your comment stating that the English in the paper needed improvement, we sincerely appreciate your feedback. We acknowledge that there were areas in the manuscript that required further refinement to enhance the clarity and coherence of the language. We are committed to addressing this concern effectively and ensuring that the manuscript met the high standards expected for publication.

To improve the English expression, we carefully reviewed the entire manuscript and made necessary revisions to enhance the overall language proficiency. The red words in the revised manuscript represent the parts that have been modified for improved clarity and accuracy.

We thank the reviewer for bringing this matter to our attention and providing us with an opportunity to enhance the clarity and quality of our paper. We assure the reviewer and the editorial board that we made every effort to address this comment effectively and submitted an improved version of the manuscript.

Sincerely,

Sukyoon Oh

Author Response File: Author Response.docx

Reviewer 3 Report

After reading through the revised manuscript, the author finds the overall quality has been greatly improved. Most of the edits, especially the Abstract, have now made the article easy to understand, where the reviewer finds it better to evaluate the quality of the research. Overall, the proposed research sounds correct and viable. 

However, all the imaging and simulation experiments were conducted on a single object structure (4x transparent rectangles on a black background). It is not quite convincing that DG speckles patterns are the optimal solution for "complex or unknown shapes", as claimed in the article.  Conducting experiments on a few different object structures is helpful to justify the robustness of proposed reconstruction methods. 

Author Response

Dear Reviewer,

Thank you for your positive feedback on the revised manuscript. We appreciate your acknowledgment of the improvements made, particularly in the Abstract, to enhance the clarity and understanding of the article. We have taken your comments into careful consideration.

Regarding your concern about the limited scope of our imaging and simulation experiments on a single object structure (4x transparent rectangles on a black background), we understand the importance of validating the robustness of our proposed reconstruction methods for complex or unknown shapes. We fully agree with your conclusion that the sequential speckle method cannot solve the problem of achieving high-quality imaging for arbitrary targets.

Upon reflection, we accept your viewpoint and will make changes to the article accordingly. The blue words in the revised manuscript represent the parts that have been modified for improved clarity and accuracy. We will reorganize the sentences in the Abstract and Conclusion sections to align with the reply you sent, and we will incorporate the corresponding revisions. It is important to note that while the sequential speckle method may not be the ultimate solution for high-quality imaging of arbitrary targets, it can improve robustness in most cases.

Furthermore, we will emphasize that our experimental results demonstrate the effectiveness of the sequential speckle method in improving imaging quality robustness and adaptability for unknown targets to a certain extent. We will highlight that the target of the window structure in our experiments reflects different target sizes to some extent simultaneously. The cross in the figure can be viewed as a representation of target details, while the four rectangles demonstrate the imaging quality of relatively large targets. Through this selection of targets, we aim to demonstrate the robustness of our sequential speckle method.

While we regret not being able to conduct experiments on a wider range of object structures due to logistical constraints, we appreciate the importance of further investigations to establish the generalizability of our approach. In future research, we plan to expand our experimental scope to include a diverse range of object structures, allowing for a more comprehensive evaluation of the robustness and applicability of DG speckle patterns for complex shapes.

We are grateful for your valuable feedback, and we assure you that we will reorganize the sentences according to your suggestions and make corresponding revisions in the Abstract and Conclusion sections. Thank you for your consideration.

Sincerely,
Sukyoon Oh

Author Response File: Author Response.docx