Experimental Generation of Structured Light Beams through Highly Anisotropic Scattering Media with an Intensity Transmission Matrix Measurement
Round 1
Reviewer 1 Report
In this paper, the authors present a novel scheme to reconstruct structured light beams through highly anisotropic scattering media, which is based on intensity transmission matrix measurement. This is a topic of high importance for developing optical applications such as high resolution imaging and optical manipulation that depends on structured light beams through the highly scattering media including biological tissue and multimode fiber. Compared with the conventional method which relies on the measurement of complex-valued transmission matrix, this scheme is easy to implement, fast and stable. The theoretical principle has been clearly clarified in the paper. Experimentally, three kinds of structured light beams such as Bessel-like beams, vortex beams and cylindrical vector beams were constructed experimentally through a ZnO scattering layer. Overall, the article is well organized and can be accepted for publication. I just have a few minor remarks that the authors should address before publication:
1. What’s the distance between the ZnO scattering layer and the focal plane. This is an important parameter to understand the experimental data. Please add it in the part of experimental setup.
2. Line 68-69: “Compared to the conventional TM calibration based on four phase method, our measure times is short to half.” Why? Please add some explanation on this point in the paper.
3. The provided “Summary and Conclusions” is more just a summary. Please revise this section, which would also benefit from some discussion.
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
In their manuscript “Experimental generation of structured light beams through highly anisotropic scattering media with an intensity transmission matrix measurement”, Lei et al. present an approach on forming structured light beams by measuring an intensity transmission matrix. The existing method of constructing structured light beams through a highly anisotropic scattering medium (HASM) usually requires measurement of the complex-valued transmission matrix, which poses a demand on the the holographic methods and depends on a reference setup. To simplify this process, the authors designed an approach which only requires measurement of an intensity transmission matrix. The researchers not only provide theoretical description of their approach, but also demonstrate experimental generation of three typical structured light beams such as Bessel-like beams, vortex beams and cylindrical beams. In total, the manuscript is well written, the experimental approach as well as results are technically sound and convincing. However, I have some comments on how to improve the manuscript prior its acceptance/publication. I provide my comments below.
1. A DMD is applied to achieve binary amplitude modulation and obtain focusing through scattering media. Is this method used in any published paper? Add some relevant references in the manuscript.
2. To construct structured light beams through HASM, the authors use a real filter to filter the Fourier field of the output plane. In comparison, the existing method [Ref.26] applies a special filter mask in a virtual Fourier plane of the output modes of the experimentally measured TM. Some sentences should be added to compare these two methods. For example, what are the advantages of the these two methods?
3. In the experimental results such as Figure 4 and Figure 5, some fluctuations exist in the intensity distribution of the donut beams. Is there any method to improve it? Please discuss this point in the manuscript.
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
In this manuscript, the authors present a transmission matrix-based technique for the creation of structured PSFs through scattering materials. This method's efficacy was validated by the generation of Bessel-like beams, polarized beams, and vortex beams. Distinct from early studies utilizing optical phase SLMs, the authors employed an intensity-only DMD to shape the wavefront. This could, theoretically, reduce instrumental requirements and simplify experimental procedures. The research is robust and intriguing, but several points need to be addressed prior to its publication.
1) The use of physical masks to shape the Fourier plane light field marks a noticeable divergence from other similar studies. The necessity for this mask remains unclear, as it adds complexity to a setup where digital filters could be applied. This aspect should be discussed in the introduction and/or the conclusion. How do the authors compare this strategy with the commonly used digital filters, such as in Boniface's work (Optica Vol. 4, Issue 1, 2017)? Additionally, could a programmable SLM/DMD replace this pre-made mask to produce more complex PSFs?
2) In the images of the polarized and vortex beams, prominent background speckles are evident. Is there a connection between this phenomenon and the utilization of intensity-only TM coupled with the imperfections of the physical masks? How would one improve the SNR?
3) What is the time required to conduct the TM-calibration? Furthermore, how robust is this method against the dynamics and misalignment of the scattering media?
4) Is this method applicable to wide-field structured illumination?
5) Could this technique be employed for practical applications, such as multimode fiber endoscopes? If this is feasible, where would the physical phase mask be positioned?
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 3 Report
The authors have thoroughly addressed my concerns in the revised manuscript. I recommend the publication of the manuscript in its current form.
