Ghost Fringe Suppression by Modifying the f-Number of the Diverger Lens for the Interferometric Measurement of Catadioptric Telescopes

Round 1

Reviewer 1 Report

In this manuscript, the cause of ghost image and the method of suppressing ghost image are analyzed in detail when measuring the WFE of the catadioptric telescope by interferometer. One method is reducing the size of pinhole, and the other method is choosing a suitable F-number diverger lens (standard Transmission Sphere). In my opinion, the innovation of this manuscript is not very strong, but it has strong engineering practicability. It can provide technical guidance for interferometric measurement of catadioptric telescope.

However, there are still some problems in the manuscript. If the author can seriously modify the following problems, the manuscript can be accepted.

1.All the figures in the manuscript are too rough. For example, Figure 1 is clearly derived from Zemax, although the drawing and layout are not very beautiful, it can also show that this is a catadioptric telescopic system. But Figure 2 almost borrows from Figure 1, just adding an interferometer. If the optical structure of Figure 1 is right, Figure 2 can be understood as a wrong structure. In addition, Figure 10 is almost identical to Figure 11, except that Figure 10 has comments and Figure 11 does not. What do you want to express with these two figures? Figure 15 looks exactly like Figure 11, why? The text comments in Figure 20 are not legible. Where is the WFE diagram in Figure 20? It is hoped that the author can carefully modify all the figures (from Figure 1 to Figure 21) to clarify the role of each figure in the manuscript.

2.The illustration of glass in Figure 6 is also very unprofessional. The optical path distribution in Figure 10 shows very messy, and I'm not sure if it’s correct.

3.All figures in the manuscript should be referenced in the text. The author forgets some illustrations, such as Figure 4. I don't even understand the role of Figure 4 in the text.

4.When referencing to the figure in the manuscript, the author is quite casual, such as "Figure 2", "Figure.5", and "figure 20". It seems that the author's writing is very casual.

5.Some professional words in the manuscript are difficult to understand, such as "mirror coating".

6.What does the mean of "AC Flat" in Figure 10? What's the full name?

7.The manuscript proposes that choosing a suitable F-number TS can effectively suppress ghost fringe. But as we all know, whether Zygo interferometer or 4D interferometer, the F-number of its standard TS is limited. You can't have any F-number you want. If the F number obtained by the simulation analysis happens to be absent, and the standard TS with other F numbers cannot suppress the ghost image, what should we do?

Please improve English and engage native proof-reader if available.

Author Response

Thanks to the editor and the reviewers for giving constructive comment and suggestion on the manuscript. The reply to each comment and corresponding revision are as attached.

Author Response File: Author Response.pdf

Reviewer 2 Report

I have reviewed the manuscript titled "Ghost Fringe Suppression with Modifying f-Number of Diverger Lens for Interferometric Measurement of Catadioptric Telescope," which shares the experimental design and results demonstrating ghost fringe suppression during the measurement of wavefront error in a Catadioptric Telescope. I have found it to be technically sound with carefully conducted experiments. However, the presentation of the paper lacks clarity and coherence, making it less impactful for readers. As such, I cannot recommend this paper for publication in its current form. It requires significant revisions throughout.

Recommendations:

Introduction: The introduction lacks a broader impact and clear motivations for why the Catadioptric Telescope was chosen for the earth observation mission and where the results of this paper are useful. It would greatly benefit from including references supporting the significance of catadioptric telescopes for current and future planned space missions and the importance of your wavefront measurement. 

Example reference: https://ui.adsabs.harvard.edu/abs/2009SPIE.7478E..0WB/abstract

These numbers come out of the blue:

Why the 40cm telescope diameter?

Why the 14 cm secondary diameter?

Methods: Source of Ghost Fringe for Catadioptric Telescope: Please add an introductory paragraph explaining how the interferogram was obtained, including details about the laser used (He-Ne laser 632.8 nm), the test surfaces, and the camera. This will enhance the reader's understanding of the experimental setup.

Results: I appreciate the quality of the experiment and results, however, improvement in the presentation is needed. I had to do a lot of guesswork to understand them. Figures need to be more informative and adequately labeled. It is essential to provide clear descriptions of the experimental setups and how to interpret the obtained data.

Figures: Each figure should include sufficient labeling of elements and clear captions describing the experimental setup. Some redundant figures. 

Specific recommendations for improvement include:

• Figure 1 and Figure 2: Please describe all elements of the system in the figure caption. Label components such as the diverger lens, flat mirror, and pinhole for easy identification. For example, see Figure 10.
• Figure 4: Clarify the experimental setup and provide definitions for labels F1-F5. Interpret the results. Additionally, include color bars indicating wavefront error in nm.
• Figure 6: Define terms such as L1S1 -- L4S2 in the body text for clarity.
• Figure 9: Include color bars indicating wavefront error in nm.
• Remove redundant figures such as Figure 11 and Figure 15, which are duplicates of Figure 10.

Correct typos throughout the manuscript, such as "Interfergram" to "interferogram" and "Base on" to "based on."

Author Response

Thanks to the editor and the reviewers for giving constructive comment and suggestion on the manuscript. The reply to each comment and corresponding revision are as attached.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

After the author's revision, I think the manuscript can be accepted.

Author Response

Thanks to the reviewer for accepting the manuscript. The further revision has been completed with adding more references of introduction section and correcting the figure caption to avoid the confusion for reader.

Reviewer 2 Report

Thank you very much for the improvements; this revised version looks much better. However, I believe minor revision is required before the publication. 

Main concern: Figure captions should be standalone, meaning they should be descriptive enough to be understood without having to refer to the main text. For example, in Figure 4, the caption "Full field WFE maps" does not adequately explain the complexity of the figure. Another example, In Figure 1, the reader may have questions about the meaning of the colored rays. Please add text that is descriptive enough to understand each figure standalone.

Optional recommendations: 

Lines 26-38: In the first paragraph of the introduction, the authors described where this work is useful and relevant but did not support it with relevant references. There is only one reference. Could you please add more citations to increase the impact of your work?

Line 45: Add a sentence. Consider adding a brief line: "The optical quality of the entire system is usually measured with an interferometric measurement."

Minor editing of English language is required

Author Response

Thanks to the reviewer for giving further comment and suggestion on the manuscript. The reply to each comment and corresponding revision are listed as attached.

Author Response File: Author Response.pdf