Investigation of an Improved Angular Spectrum Method Based on Holography
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
This article has sufficient contents with analysis and comparison of the three holographic algorithms; however, there are still some comments and suggestions for authors with major revision as follows:
1. Many previous researches of digital holography utilized spatial light modulator (SLM) (i.e. phase modulation type LCOS) with developing holographic algorithm method to achieve high quality and ultra-high resolution reconstructed image by phase corrected algorithm, more fined 3D depth information, and dynamic image analysis for optical microscopy, which these are important references in “Introduction” part. On the other hand, the research mentioned about digital holography for biomedical optics application were also not enough references into “Introduction”. The reviewer suggests that add more references about digital holography with SLM and utilized into biomedical optics application.
2. This paper claims that the improved holographic technology by using high SNR and depth information to improve optical microscopy for biomedical optics; however, its depth distance is too large about a few ~10 cm to useful into optical microscopy under fined 3D distance about mm ~ μm level requirement. The reviewer suggests that add mm ~ μm level diffractive 3D distance experiment and analysis or clearly explain the challenge and difficulties in the current technology for readers to understand.
3. The model of optical experimental equipment (ex. CCD / Lens…) and the software version used by the optical algorithm should be clearly disclosed in the manuscript.
4. The important part of biomedical optics not only requires fined different distances to achieve more 3D depth information from microscopic imaging, but also need ultra-high resolution (>4K2K or even 8K4K) image to get more detail bio-information; however, this study discussed the DH results under low resolution (256x256). The reviewer suggests that add >2K1K level holographic reconstructed image experiment and analysis or clearly explain the challenge and difficulties in the current technology for readers to understand.
5. The calculation time of the optimized algorithm and the high imaging quality are often trade-off with each other. The article only mentions the difference results of RMSE and energy map under these three methods, but not reveal the running time of these algorithms. The reviewer suggests that add the comparison of calculation time between the optimized algorithm and traditional method, and also disclosed the runtime environment (ex. choose which GPU to run…).
6. The “References” part has many mistakes with format cited method and there are many no unified format between each references. (ex. Abbreviation of Journal, “[J]”???, don’t need month, “Vol”, “pp” can be omitted, just need Number…).
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors
1) I suggest explaining in a more rigorous and mathematical way the methods and algorithms used in the work. The explanation and theoretical support for them is basic or null.
2) References need to be improved and updated.
Comments on the Quality of English Language
The quality of English is moderately good, a general review is suggested.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for Authors
The work submitted by Ting Wu et al., based on digital holography, an intersection between optics and biomedical sciences, offers significant advancements in real-time imaging and dynamic monitoring, especially in biological cell imaging. This study introduced an enhanced angle spectrum algorithm tailored for holography. The authors claim its superior performance in cell image reconstruction, particularly in high signal-to-noise ratio.
This reviewer's opinion is that it is a noteworthy contribution to cellular detection in clinical diagnostics once digital holographic microscopy emerges as a versatile tool for tasks such as microparticle imaging and cell observation, given its capacity for non-invasive, dynamic, and quantitative analysis. In essence, this research showcases the potential of the improved angle spectrum method, heralding new horizons in holographic applications, especially in biomedical imaging and diagnostics.
Section 2, "Holographic Principle," is well explained and written with no excess of equations and two flow charts, offering a good reading experience.
However, in the revised version of the manuscript, particularly in section 3, "Methods", the authors should present the method's steps 1 to 5 (lines 182-217) differently, for example, creating an introduction paragraph mentioning the following steps in the form of bullet points. Also, in section 4, figures should be arranged, e.g., figures 4 and 5 should be in the same figure, as well as figures 11 and 12 and 23 and 24. There is no point in presenting Figure 20 in the manuscript (if the authors wish, they could do it in SI) once the text description of the figure is enough. Figures 21 and 22 should be a single row with a 3-column size figure because the relevance is the energy phase energy by different algorithms represented by color levels. Therefore, the graphs can be smaller and stay side-by-side in a single row. In sum, the figures re-arrangement must be made to continue giving a good reading experience.
This reviewer also agrees with the authors that traditional optical microscopy captures only amplitude information like the brightness and color of cells. In contrast, phase information reveals intricate structural and morphological details, such as cell nucleus position, internal hierarchical structures, and cell membrane shape, which are vital for understanding cellular functions and pathologies. Nevertheless, the authors must discuss, in the revised version of the manuscript, the following topic:
- Can the author's approach be applied to the two-photon excitation microscopy technique? Justify the answer with examples and references.
The authors claim that the presented methodology offers advantages in detecting abnormal chromosomal cells and diagnosing significant diseases by analyzing irregular cell shapes and numbers. The method's precision in spotting live cells and cytoplasmic anomalies heralds potential in biomedicine. In the revised version of the manuscript, the authors must justify this claim with a more detailed discussion and references.
For example, in cellular motion and activity, in particular, understanding cellular or subcellular movement can be achieved by analyzing biological laser speckle images. In order to enrich the manuscript discussion, could the authors discuss the advantages and disadvantages of using traditional optical microscopy post-processing by the developed algorithm versus laser speckle imaging (LSI)? Could their post-processing algorithm be applied to LSI?
Comments on the Quality of English Language
Minor editing of English language required
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for Authors
This revised article can be accepted, even if the research also not yet develop more fine depth focus from ~cm to ~mm or ~um level and higher image resolution for real bio-medical application. At least the paper clearly shown the difficulties and challenges with addition supplementary notes.
Author Response
We are very grateful to the experts for reviewing and commenting on our paper. We attach great importance to the experts' comments and will seriously consider them and try our best to make changes accordingly. We will make further efforts to explore new techniques and methods to improve image resolution and depth focus for higher level biomedical applications. In the revised paper, we will describe in more detail the challenges and difficulties we faced and state our expectations for future techniques and methods. We believe that with these refinements, the paper will more accurately reflect our findings and contribute to research in related fields.
