Dynamic Measuring Method of Laser Beam Incident Angle for Laser Doppler Vibrometer

Round 1

Reviewer 1 Report

In the manuscript Dynamic Measuring Method of Laser Beam Incident Angle for Laser Doppler Vibrometer, the authors report a new dynamic measuring method for the laser beam incident angle of LDV. By using a rotating disk and a vibrometer, the authors experimentally demonstrated a high precision measuring device to dynamically monitor the incident angle of the laser, as well as presenting a complete error analysis.

The concept is clear. The data displayed is convincing, and strongly supports the conclusion. In principle, I think this work could be suitable for publication in MDPI Applied Sciences with minor changes on the draft.

Minor suggestions:

1.      The experimental design for the static measurement can be improved. When measuring angle beta (section 3.2), the vertical distance l is well controlled within 1 um resolution, while the other distance d is measured by iphone camera and coordinate paper. According to table 1, d has measurement precision of 1 um (3-digit resolution) – I doubt how this precision can be achieved on a coordinate paper based on the following considerations:

a.      The calculation of beam center is tricky,

b.      Typically, camera resolution is a few microns.

c.      When the focus of the laser beam is adjusted, it might move more than 1 um.

2. For the dynamic angle measurement experiment, the device always measures the relative angle between the laser and the wheel, instead of the laser itself. That is to say, the reference, i.e., angle of the wheel, will limit the precision of the system (the authors also point this out). Practically, if the spinning wheel represents the wheel on the vehicle, how could we use the object to be measured (the wheel) as the reference to calibrate the measuring tool (the laser)? This is a chicken-and-egg problem.

3. The introduction can be succinct. The authors describe former methods in great detail, e.g., line 51-118, which might not be necessary and can distract readers. Authors should highlight the connection between the former research and this work, clarify the flow, and trim the details.

4. Authors could use graphs/figures more wisely. In principle, each figure should tell its own story and have key information to deliver. Some figures, e.g., figure 4, only show images of equipment with no conclusion drawn - I suggest removing these figures since it has no information. Also, the caption of the figures should be complete and captions in this paper draft can be improved, e.g., caption in figure 7, 10, etc.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Review Report on "Dynamic Measuring Method of Laser Beam Incident Angle for 2 Laser Doppler Vibrometer" Summary: The paper under review presents a method for dynamically measuring the incident angle of a laser beam, with specific application to 2 Laser Doppler Vibrometers.  The article introduces a novel method, which could provide significant advancements in the field of laser beam measurement. This method's uniqueness potentially allows for more accurate and dynamic measurements, enhancing the current methodologies available. Areas for Improvement: Lack of Clarity: One of the primary areas of concern is the clarity of the content. The article at times resorts to technical jargon and complex terminologies without adequately defining or explaining them. For professionals already well-versed in the topic, this might not be an issue. However, for a broader audience or those new to the field, such language could make comprehension difficult. Clear definitions and perhaps a glossary section might aid in improving understandability. Limited Scope: While the paper delves into the specific method of measuring the incident angle, it doesn't expand to offer a broader context. Understanding the relevance and application of this method in the grand scheme of laser beam measurements or its potential in various industries would add value to the article. By juxtaposing this method with existing techniques, readers could gauge its relative advantages and disadvantages better. Limited Validation: The validation process leans considerably towards simulation experiments. While simulations are vital and provide insights into how a method might perform under controlled circumstances, they often fall short of replicating the unpredictability and complexities of real-world scenarios. Introducing experiments using real-world data or situations would solidify the method's reliability and applicability. Or such work could be given as references for comparison. Lack of Discussion: Post-results, the paper could benefit from an extensive discussion section. Delving deeper into the implications of the findings, exploring the method's limitations, and suggesting directions for future research could give the article a well-rounded finish. Such discussions not only enhance understanding but also foster further research and inquiry into the topic. Conclusion: The "Dynamic Measuring Method of Laser Beam Incident Angle for 2 Laser Doppler Vibrometer" undoubtedly makes a notable contribution to its field. Its innovative approach could be instrumental in refining the processes associated with laser beam measurements. However, the article could elevate its impact and clarity by addressing the mentioned areas of improvement.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf