Readout System for Multipurpose Real-Time and Portable Spectrometer

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

 

This paper presents a solution for utilising a Hamamatsu C12666 single-chip spectrometer.

 

Overall, I am not convinced that the paper in its current form offers the reader enough to be useful in understanding how (and whether) the system works as intended, and also misses some highly relevant projects that have used the same or a closely related spectrometer chip.

 

 

Major issues:

The paper is focused almost exclusively on electronics, and barely touches on the spectroscopy. E.g., is the system intended for radiance or reflectance spectrometry?

 

There seems to be a lack of calibration data, e.g. demonstration of the linearity of the response, the spectral sensitivity response etc… Not only are these missing, but these issues are not highlighted to readers.

 

The system’s behaviour has not been described in sufficient detail for a reader to understand some essential design decisions. e.g. how is the dark current measured and managed in use, how is the integration time set, how is saturation dealt with etc...

 

Data availability – the code used for the project has not been made available, so cannot be reviewed. Without the data to show how the system works relative to calibration data, and to understand system behaviour, reviewers and readers can’t determine whether the system works as intended.

 

The paper doesn’t mention previous peer-reviewed projects that have used the same chip and released open source code to read the data directly to a simple microprocessor. e.g. https://github.com/impfs/review and https://doi.org/10.1242/jeb.245416. What is offered by this system above and beyond the existing implementations?

 

 

Minor issues:

 

The abstract mentions the C12880 chip, but most of the manuscript refers to C12666 – requires clarity.

 

“MEMS-based spectrometers” – what are these? The acronym needs defining.

 

A beaglebone with ARM Cortex A8 processor is overkill for managing a sensor with only 288 photosites. At least this process power needn’t be advertised as though it is required.

 

Using an OpAmp for the video pin might make sense for lowering the sensor current, however in my experience the sensor performs very well with long (30 second) exposures without this, and the chip stays at a stable temperature.

 

The manuscript mentions that functions have been obtained from GitHub. These need citing (particularly peer-reviewed papers), and care needs to be taken to work out what licenses cover the re-use of this code etc…

 

I’m not sure what figure 7 adds? Surely a useful calibration would compare the output of a known spectrum?

 

There is a lot of speculation regarding future improvements (e.g. white rabbit and fuzzy logic), and far too little detail on how the system actually works.

 

 

 

Author Response

Find the answers in the pdf

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript presents a solution for a compact and versatile spectroscopy system. Integrating a Hamamatsu C12880 spectrometer module with a BeagleBone board creates a platform for various applications. The system's claimed ability to measure a wide spectral range and its ad-hoc customizable electronics might make it adaptable to diverse scientific and technical scenarios. The proposed spectrometer system might demonstrate significant potential for various applications. Further development, particularly in FPGA migration and real-time processing, could significantly enhance its capabilities and impact.

Some issues that the authors should address:

To strengthen the evaluation, the authors should consider a more in-depth analysis of the system's sensitivity, resolution, and noise characteristics. A deeper exploration of the system's real-time processing capabilities and limitations would also be beneficial. In this regard, discussing the system's potential use in modulated reflectance experiments, such as photoreflectance and reflectance difference spectroscopy (RDS/RAS), could provide valuable insights and extend the interest to a broader user community.

Another serious issues:

Fig. 3 is not acceptable. It looks like a copy-paste of the image from another document. In such a case, the authors must cite the source. 

Schematics (fig. 4) is barely appreciated: it must size up.

Is figure 5 essential?

Figs. 6  and 7 captions must be elaborated, and such figures' content is not acceptable in the scientific community.

Please make the document serious enough.

 

 

 

 

 

Comments on the Quality of English Language

The quality of the English must be improved.

Author Response

Find the answer in the pdf

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I thank the authors for their feedback and the manuscript adjustments. 

Author Response

Thanks for your help.