A Picometre-Level Resolution Test Method without Nonlinearity for Heterodyne Interferometer Measurement Electronics
, Wenjun Li 1,2, Xu Xing 1,2,*, Jianing Wang 1,2, Pengcheng Hu 1,2 and Jiubin Tan 1,2Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn this paper authors report on a resolution test method for the heterodyne interferometer measurement electronics that handle well the nonlinearity and as a good applicability potential. The use of AOM modulators is not new and the fact the method allow picometer resolutions a couple of times better than previously published methods results, is not impressive and it is clear that there is space for improvment (in fact the authors point out line of future development, that could be incorporated in this report and would certainely improve the value of the paper significantly). However the work has merits and deserves being published. Please revise carefuly the English writing...
Comments on the Quality of English LanguageRevising is needed, several grammar problems must be solved and phrasing improved.
Author Response
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Reviewer 2 Report
Comments and Suggestions for AuthorsBy intensity modulation signals with AOM, a picometer resolution test method for measurement electronics has been proposed in the article
Some descriptions should be corrected or modified,
Line 38/39: This means that resolution of measurement electronics is the highest that heterodyne interferometer can achieve theoretically.
Line 48/49: the signal-to-noise ratio of the electrical signal from the photodetector may not be able to support the phase meter to achieve its highest theoretical resolution.
Line 68: there is an obvious nonlinearity that has not been solved.
Line 95: the errors from optical structure are able to reach tens of nanometers
Line 98: photodetector is a big error source composed of 98 two categories
Equation (3) should be revised, for this optical path N=2 in numerator.
Symbol for Phase x in Equation (4) is incorrect.
With Figure 2, detailed expression about the interference signal developed on PDm is required.
Author Response
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Reviewer 3 Report
Comments and Suggestions for AuthorsThis paper describes a new test procedure for measuring picometer resolution that can be used to assess the performance of measurement electronics in heterodyne interferometers. To accurately evaluate the performance of the measurement electronics, the study uses intensity-modulated signals to evaluate the resolution of the interferometer measurement electronics.
There are some problems and suggestions that need to be solved and considered by the authors.
1. The relationship between the phasemeter's measurement results and the actual phase change brought about by the target displacement is expressed by the authors using Equation (4). Why is it necessary to multiply the photodetector's phase error by a particular constant? The same question is posed in Equation (13). Please explain the reason or give details of the derivation.
2. In Section 3.1, the author presents the "zoom factor" to demonstrate the superiority of the suggested approach; however, the author merely provides a formula, leaving the derivation process unclear. Furthermore, it is not explained in detail how reducing the mirror's displacement can be achieved by changing the AOM's modulation frequency.
3. The simulation mentioned in line 205 needs to be described in more detail.
4. The authors of section 4.3 analyze the experimental data and propose that fluctuations in light intensity are the cause of the nonlinear error. Please elaborate on the physical mechanism underlying this correlation or offer more experimental evidence in favor of this theory.
Only after the above issues and ideas have been thoroughly addressed and examined will the article be published in Photonics.
Comments on the Quality of English Language
A excellent research article must be easy to read and well-written in English. This page is largely readable, however there are a few grammatical errors and what appear to be machine translation remnants. As in lines 136 and 142, respectively, with reference to "the other convex" and "air refractive index perturbation". It is recommended that the authors revise and restructure the article to improve readability.
Author Response
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Round 2
Reviewer 2 Report
Comments and Suggestions for Authorsno comments
