Wavefront Sensing by a Common-Path Interferometer for Wavefront Correction in Phase and Amplitude by a Liquid Crystal Spatial Light Modulator Aiming the Exoplanet Direct Imaging

Round 1

Reviewer 1 Report

Please see my uploaded review report.

Comments for author File: Comments.pdf

Author Response

Please see in attached file

Author Response File: Author Response.docx

Reviewer 2 Report

The authors develop an interferometer to control the wave phase and amplitude with a LC - SLM for exoplanet imaging. The methods based on rotational shear interferomtry are well introduced as well as the the technics of wavefront measurements. The manuscript is correctly written and proposed method based on SLM is novel  and may have the potential characteristics in view of  exoplanet imaging and interferometric suppression of the on axis image. This part of the paper is well developed including several optical schemes of interferometers, wavefront measurements, corrections and simulations. I outline the following questions about the  experimental part with the SLM : 

- When using a LCSLM it introduces a low level of scattered light and also it generates a diffractive structure due to pixels. How these effects will affect the functions and performances of the coronagraphic images. 

-The phase aberrations of the LC SLM substrates as well as, the limited phase precision on each pixel versus applied voltage, optical transmission of the polarized light, sensitivity to temperature, are certainly limiting factors of the contrast. Comment and estimate  required values on these parameters to attain the performances of the coronograph.

- Is there a limitation about the response time of the SLM and CCD detectors with respect to time evolution of the perturbed wavefront. Consequences  for real time wavefront measurement by phase shifting interferometry and influence of the noise of the CCD detection detection to limit the contrast.

To conclude the paper brings a significant new contribution to the field of coronography using an AO-SLM for exoplanet imaging. The paper includes an extended analysis of the problems and details on the experiments, simulations of  wavefront correction in different conditions. It is well suited for publication in the Journal after taking account of the above questions and comments in the final form. 

 

 

Author Response

Please see in attached file

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The authors have answered the questions and comments listed in my first review report. I recommend the revised manuscript for publication. 

Reviewer 2 Report

The authors have correctly answered to the questions relevant to the properties of the used LC-SLM in terms of wavefront quality, response time, and optical efficiency. A new reference on this subject. The text now includes more developments on the coronographic PSF suppression in focal plane and coronographic contrast. According to these complementary datas the paper can now be considered for publication in the journal.