Study on the Optical Properties of the Point-Focus Fresnel System
Round 1
Reviewer 1 Report
The authors present an efficient method of simulating luminous flux transfer in a heliostat, using a Gaussian flux approximation. They compare their approximation with numerical ray tracing and find good agreement. The research is not very novel, but the results are correct.
One specific recommendation is to remake the figures. The plots of the simulation results are difficult to read because of small font sizes and poor image resolution.
Revised review of “Study on Optical Properties of the Point-Focus Fresnel System” by Fei Shen and Weidong Huang.
The authors present an approximation technique for modeling the flux transfer of a heliostat array based on a Gaussian flux approximation. This is an extension of the author's earlier work (Ref. 6) from a single heliostat to an array of 15 heliostats. The calculations compare the authors' approximation with a ray tracing calculation using a standard software package. The paper relies heavily on the authors' previous work, and the "Materials and Methods" section is lacking some context, e.g. by reusing the equations from the earlier work without defining the variables.
The results seem correct, but they are not novel. The discussion of the results is also insufficient. While the differences between the Gaussian approximation and the ray tracing simulations are small, the authors should try to explain these differences on physical or mathematical grounds. They propose a list of possible causes for the remaining error, but these are vague and the authors do not attempt to validate any of these.
The major benefit claimed by the authors is that their method requires less computation time compared to ray tracing, but they do not quantify this gain. With modern computer power, the ray tracing does not seem difficult for this relatively simple optical system. (The authors use 5 million rays, which is not an unusually large number.) The other use of analytical approximations is to provide insight into underlying physical processes, but this aspect is not discussed in the manuscript.
There are also minor formatting issues: the text in the figures is too small/poor resolution and the bibliography entries are not consistently formatted.
In summary, I believe the paper requires major revisions before publication to address the above items.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Please see the attachement file.
Comments for author File: Comments.pdf
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
I am satisfied with the revisions made by the authors. I now recommend publication.
Reviewer 2 Report
The author has provided a complete response to the previous amendments. Overall, the current version can be accepted and published.
