Extending the Imaging Depth of Field through Scattering Media by Wavefront Shaping of Non-Diffraction Beams

Round 1

Reviewer 1 Report

The paper is devoted to the use of wavefront shaping technique for extending the imaging depth of field through scattering media. The paper could be useful for the community and could be published, but after a major revision. In my opinion, before considering its publication, authors should address a few issues. 

First of all, there are a few major corrections that have to be done.

  1) Lines 111-118. Imagine you set the values of the SLM pixels for the first group of pixels. Your merit function (intensity in the focal plane) is increased. Then you reset the values of the pixels from the first group and use the pixels from the second group. Merit function is increased again. 

  It is not clear why the combination of independent groups of pixels on the SLM should increase the merit function. Each individual group of pixels can increase it, but when you combine let's say two groups the second group can degrade the result achieved by the first group. If it is not the case, it have to be explained in the text.

  2) In line 200 you write "It can be seen that the in the coherent illumination". In line 201-202 you write "The same with coherent illumination,"

  I guess it should be "incoherent" somewhere. But where exactly?

    3) Since you are writing about the results obtained using the algorithm ISC-GA (reference #19), it would be better to briefly describe this algorithm in the text of the manuscript.

Second, the reference list is sparce. For example, why do you use spatial light modulator? Why not to try another phase shaping devices that are also used for this purpose? What are the advantages and disadvantages of SLM vs bimorph mirror vs stacked-actuator mirror vs MEMS? I would strongly recommend to take a look at the following papers and add it to reference list (and any other references the author will find useful):

- C. Stockbridge, Y. Lu, J. Moore, S. Hoffman, R. Paxman, K. Toussaint, T. Bifano, "Focusing through dynamic scattering media," Opt. Express 20(14), 15086-15092, 2012.

- I. Galaktionov, J. Sheldakova, A. Nikitin, V. Samarkin, V. Parfenov, A. Kudryashov, “Laser beam focusing through a moderately scattering medium using bimorph mirror,” Opt. Express 28, 38061–38075 (2020)

- D. C. Chen, S. M. Jones, D. A. Silva, S. S. Olivier, "High-Resolution Adaptive Optics Scanning Laser Ophthalmoscope with Dual Deformable Mirrors", Journal of Optical Society of America, A, 2006.

- I. Galaktionov, A. Nikitin, J. Sheldakova, V. Toporovsky, A. Kudryashov, "Focusing of a Laser Beam Passed through a Moderately Scattering Medium Using Phase-Only Spatial Light Modulator," Photonics 9(5), 296, 2022

- Zahid Yaqoob, Demetri Psaltis, Michael Feld, Changhuei Yang, "Optical phase conjugation for turbidity suppression in biological samples," Nature Photonics 2, 110-115, 2008.

Third, all of the grammatical and punctuational errors should be corrected - change "will be caused" to "will cause",

- "randomly" to "random" in the first paragraph of the Introduction, 

- line 86 "using an light field" - change "an" to "a",

- line 200 "It can be seen that the in the coherent illumination" - remove "the"

- etc.

In general, the quality of english is good enough. The text contains only a few small errors that have to be corrected

Author Response

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Reviewer 2 Report

In this paper, the authors extended the depth of field (DOF) through scattering media by combination of wavefront shaping and non-diffraction beams. Compared to Gaussian beam, the DOF of Airy beam was improved by a factor of 1.5 in coherent illumination. Moreover, in incoherent illumination, the DOFs were improved by a factor of 1.1 and 1.5 by Bessel beam and Airy beam, respectively. The technique may have potential applications in many other scenes such as biomedical imaging, but it still has some practical questions as follows before it is considered for publication:

1. As mentioned in the article, the refocused spot has a PBR value of "980", but the calculation method is not given. It would be good that the authors explain how this value was obtained?

2. The authors consider the cases of coherent and incoherent imaging and give the imaging formula for the incoherent case. How is this different from the coherent case?

3. What images are used as reference to calculate PCC, SSIM and PCC? Please mark them in Figure 5 and Figure 6 or add original images.

4. In this paper, the focal plane is 0 coordinate, and the images are located in the corresponding position of positive and negative coordinates. It is better to give the definition of positive and negative of the coordinate axes.

Good

Author Response

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Reviewer 3 Report

The manuscript submitted by Tongyu Han et al. introduced a method named interleaved segment correction (ISC) to compensate the wavefront distortion caused by scattering media, and accordingly, refocusing of light and imaging of objects through scattering media are achieved. To extend the DOF, two kind of non-diffraction beams, Bessel beam and Airy beam are generated behind the turbid media. The authors present the principle and experimental data in a scientific way, however, it still has some questions as follows:

1. The author introduced an improved GA, or namely, the ISC-GA method. However, in the experiments, the number of segments and the pixel number of each segment are not given, please add it. How the parameter influences the efficiency of refocusing?

2. In the results of Figure 5 and Figure 6, it is better to give the reference images for image quality evaluation.

3. What’s the distance between the scattering medium and the object, it is not clarified in the manuscript. Does this distance affect the quality of the imaging result?

Author Response

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Reviewer 4 Report

The paper entitled ‘Extending the imaging depth of field through scattering media by wavefront shaping’ proposed by Tongyu Han et al. details their research on extending the DOF via an improved algorithm, validating via two types of non-diffraction beams (Bessel and Airy). The paper is well-organized and has been written in a logical manner. I also appreciated the authors have done experiments to validate and support their claim, which is quite convincing. I only have a few comments that hope the authors could kindly consider before the publication.

1, I hope the author could add the discussions regarding the polarisation state of the beam profile – are all the beams feature the same, uniform polarisation state? Can the polarization of both Bessel and Airy beams be modulated further in order to achieve better DOF?

2, Can the authors comment on the limitation of an SLM that is to be used to do beam shaping? For instance, if the lens is a high numerical aperture one, is there any need that we should use multiple SLMs to do better beam shaping?

3, There are some recent references that may be useful for the authors to be considered for the future enhancement of their experiments, both in beam manipulation side or to control the wavefront: https://www.nature.com/articles/s41377-022-00897-3; https://www.nature.com/articles/s43586-021-00066-7; I hope they help.

None

Author Response

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Reviewer 5 Report

An improved genetic algorithm is used to modulate the wavefront of light through scattering media in this manuscript, where was used for extending the imaging depth of field by combining non-diffraction beam. The results and conclusion look convincing. Some minor suggestions are listed below:

1.     In Page 5, The legend of Fig.5 should explain all abbreviations in the figure, although they have already been explained throughout the main text.

2.     Also in Page 5, Line 160, “With the optimal correction phase (Figure 4b), the speckles are refocused with peak to background ratio (PBR) of 980, as shown…” what is the PBR value before correction? Furthermore, as shown in Page 4, Line 139, CCD1 is 8 bit, why the PBR value can reach 980 which much bigger than 255?

3.     In Page 7, Lines 214-218, What does “in different direction” mean? Axial or lateral? “not fully corrected” and “not fully utilized” are too ambiguous to understand.

 4.     In Page 7, Lines 218-220, maybe it is better to provide the practical time about traditional method and the improved method, respectively.

 5.     The title “Extending the imaging depth of field through scattering media by wavefront shaping” should add “non-diffraction beam”. Because the imaging depth is extended by non-diffraction beam rather than wavefront shaping which only refocused beam through scattering media.

Author Response

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Reviewer 6 Report

This paper addresses an important issue that overcoming the limitation of imaging depth of field (DOF) through scattering media. The DOF of the imaging system was extended by modulating the refocused beam into non-diffraction beams, such as the Bessel beam and the Airy beam. Experimental results show that compared with Gaussian beam, the DOF was extended effectively by using the non-diffraction beams. Overall, the article is well organized and can be accepted for publication. However, I still have some concerns as follows:

1. Refocusing of scattered light was achieved by wavefront shaping, what’s the key point that influence the quality of focusing and imaging, the author should describe in detail.

2. The author mentioned in the paper that the DOF was extended by wavefront shaping and non-diffraction beam, is there any disadvantage of the proposed method, or what can be further improved in future?

3. Refocusing of light and imaging of objects through scattering media were demonstrated, whether the proposed method can be used in dynamic imaging or in real time imaging, it should be discussed.

4. Generally, the axial intensity of the Airy beam is symmetrical along the focal plane, so both the PCC/SSIM curves should also have this trend, but it is not shown in the figure 5 and figure 6, please explain what may cause this asymmetry?

Please check the grammar of some sentences again, and the sentence should not be too long.

Author Response

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Round 2

Reviewer 1 Report

All of my comments were carefully addressed. In my opinion the manuscript can be accepted for publication in the current form