Multi-Mode Compact Microscopy for High-Contrast and High-Resolution Imaging
Ming Lei
Round 1
Reviewer 1 Report
In the manuscript entitled “Multi-Mode Compact Microscopy for High-Contrast and High-Resolution Imaging”, Kim et al. demonstrate a compact multi-mode microscopy design that simultaneously supports reflection mode, transmission mode, dual illumination mode, dark field, high dynamic range (HDR), and microlens array (MLA) assisted imaging. The authors demonstrate each imaging capability with either biological or physical samples. In particular, the HDR imaging mode increases the dynamic range of the acquired images by a factor of 1.36, and the MLA-assisted mode increases the magnification by a factor of 3.92. Overall, this paper is well organized and easy to follow. The main novelty of this work is the compact design that supports so many different imaging modalities, while almost everything else presented in this work is well known and not new. Although this work is publishable, there are many issues that need to be addressed.
1. It is incorrect to claim the MLA-assisted method as “super-resolution”. The term “super-resolution” has specific meanings in the microscopy community, i.e., beating the resolution limit set by diffraction. In this work, the improved resolution is achieved using microlens, leading to the increase of the effective numerical aperture (NA). The authors should explain the fundamental reason behind the increased resolution and refrain from using the term “super-resolution” throughout the manuscript.
2. As the major novelty of this work, the multi-mode compact design is not well illustrated. The authors only provided photographs and cartoons to show their system and operating modes, as shown in Figure 1. However, the essential parts of the design, including the full circuit diagram, the location of the processor and the circuit board, the specs of the LED and objective lens, and the arrangement of the ring-type LED array, are not provided. Besides the essential parts, the authors should provide as much information as possible on all the components used in their design.
3. According to the manuscript, the compact microscope seems to process the images by itself, without the need for an external computer. If a computer is not needed, how can the microscope display the processed images? I do not see a screen in the photographs.
4. Where is the camera, or imaging sensor? What are their specs?
5. The resolution quantification in this work is not solid. For example, the authors claim that the MCM “clearly observes group 7 element 1.” However, this claim cannot be substantiated by the profiles shown in Figure 2. The authors should use more rigorous criteria, such as the Rayleigh criterion, to quantify their resolution.
6. How did the authors obtain the spatial frequency of 135 lp/mm and 123 lp/mm from Figure 3(a)?
7. In Figures 4(f) and (g), the authors claim that the dual illumination mode can resolve the leaf hairs better compared to the transmission mode. However, the authors did not compare the dual illumination mode with both the transmission and reflection modes. I wonder if the leaf hairs can already be resolved with the reflection mode only. In that case, the dual illumination mode is unnecessary.
8. The authors claim that the HDR image processing algorithm in Figure 6(b). However, Figure 6(b) contains no useful information about the algorithm. The author should provide more details about the HDR algorithm in the manuscript.
9. The MLA + pinhole mask design is unnecessary. With a pinhole mask, the MLA behaves essentially like a single microlens. Why not simply add a small lens? Doing so, the MLA and the mask are no longer needed.
Author Response
"Please see the attachment."
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Kim et al. presented multi-mode compact microscope (MCM) that can yield high-contrast and high-resolution imaging. They achieved this microscope by using two LED illuminations, a suitable stage, a magnification lens, image processing and LED control electronics. They also demonstrated improved image resolution via the magnified virtual image of MLA by implementing the microlens array (MLA)-assisted MCM. With this approach they observed an almost 4-fold increase of resolution. This work presents a simple yet powerful microscope which can be very useful for certain applications including low-resource setting research. Overall, the manuscript is well-written and is suitable for publication. I have the following minor comments.
The abstract can be extended to better reflect the advantages of the developed microscope system
The introduction should be extended to include more examples of similar low-cost microscopes reported in the literature.
A discussion of the cost (estimated cost) of the system for benchmarking with similar systems.
Text size in figure 6 and 7 should be increased for better readilbity.
Author Response
Manuscript ID: applsci-1821143
Type: Article
Title: Multi-Mode Compact Microscopy for High-Contrast and High-Resolution Imaging
Author: Kisoo Kim*, Yeon Hwang and Jongbok Park
Author’s response for the Reviewer’s comments:
First of all, the author would like to express our thankfulness to the referees for the useful constructive comments that led to a polished manuscript (Manuscript #: applsci-1821143, “Multi-Mode Compact Microscopy for High-Contrast and High-Resolution Imaging”). The authors assure that all comments have been carefully and precisely answered to the best of our knowledge and reflected in the revised manuscript.
The main concern of the reviewer is clarity and emphasis on novelty of our research. For more details, the author revised figures to explain the principles of MLA-assisted MCM and HDR reconstruction. The author additionally explains the criteria for obtaining imaging characterization results. The abstract and introduction in the main text were extended to help the reader understand. Moreover, the advantages of our system were demonstrated through additional experiments.
Including the main concern, we have carefully and faithfully addressed the reviewer’s point-by-point comment in the attached author response as well as added more detailed descriptions in the revised manuscript, and rearranged the figure captions.
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Miniaturized microscopes has advantages of low-cost and easy integration with different systems. However, most of the current miniaturized microscopes approaches may suffer from the low contrast and low resolution shortcomings. In the manuscript entitled “Multi-Mode Compact Microscopy for High-Contrast and High Resolution Imaging”, the authors presented a multi-mode compact microscope (MCM) for high-contrast and high-resolution imaging. The authors achieved various imaging modes such as reflection mode, transmission mode and super-resolution mode.
Unfortunately, my major concern about this manuscript is its limited novelty. Miniaturized microscope is already industrialized and many companies have similar products for sale. The presented scheme is actually a small improvement of the existing Stereo microscope.
The followings are several suggestions and comments.
1. The author should draw the light path diagram of the whole system, not just give a schematic diagram of a 3D model in the Figure 1
2. In the HDR imaging mode, the author should give a detailed algorithm flow chart of the imaging method.
3. The principle description of the MLA-assisted super-resolution imaging mode is too simplistic, and the authors do not give detailed references.
4. The images in Figures 5 and 6 are of poor quality, and Figure 5 should give a comparison of brightfield and darkfield imaging modes, magnified image detail and quantitative analysis
Author Response
Manuscript ID: applsci-1821143
Type: Article
Title: Multi-Mode Compact Microscopy for High-Contrast and High-Resolution Imaging
Author: Kisoo Kim*, Yeon Hwang and Jongbok Park
Author’s response for the Reviewer’s comments:
First of all, the author would like to express our thankfulness to the referees for the useful constructive comments that led to a polished manuscript (Manuscript #: applsci-1821143, “Multi-Mode Compact Microscopy for High-Contrast and High-Resolution Imaging”). The authors assure that all comments have been carefully and precisely answered to the best of our knowledge and reflected in the revised manuscript.
The main concern of the reviewer is clarity and emphasis on novelty of our research. For more details, the author revised figures to explain the principles of MLA-assisted MCM and HDR reconstruction. The author additionally explains the criteria for obtaining imaging characterization results. The abstract and introduction in the main text were extended to help the reader understand. Moreover, the advantages of our system were demonstrated through
additional experiments.
Including the main concern, we have carefully and faithfully addressed the reviewer’s point-by-point comment in the attached author response as well as added more detailed descriptions in the revised manuscript, and
rearranged the figure captions.
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors have sufficiently addressed all of my comments in the previous review. The manuscript has been strengthened. I can now recommend the publication of this manuscript in Applied Sciences.
Reviewer 3 Report
Many thanks to the authors for their careful revision of the manuscript. But as I stated in my previous review comments, I think the experimental results of this manuscript are sound, but its biggest problem is that the experiment is not innovative enough. Miniaturized microscopes are already the commonly used commercial instruments, and I don't think the existing commercial systems have the problems of "low-image-contrast and low-spatial-resolution due to the limitations of optical power" as pointed out by the authors. Therefore, I hand over the final decision of this article to the editor, and let the editor decide whether the article should be accepted.
