the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 30 May 2024
Calibration of Optical Particle Spectrometers Using Mounted Fibres
Abstract. Calibrations of OPSs are non-trivial, and conventionally involve aerosolisation techniques which are challenging for larger particles. In this paper, we present a new technique for OPS calibration, which involves mounting a static fibre within the instrument sample area, measuring the scattering cross section, then comparing it with a calculated value. In addition, we present a case for the use of GLMT simulations to account for deviations in both minor and major axis beam intensity, which has a significant effect on particles which are large compared to the beam waist, in addition to reducing the need for a ‘top-hat’ spacial intensity profile. The described technique is OPS independent and could be applied to a field calibration tool, which could be used to verify the calibration of instruments before they are deployed. In addition to this, the proposed calibration technique would be suited for applications involving mass production of low-cost OPSs.
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RC1: 'Comment on amt-2024-55', Anonymous Referee #2, 08 Jul 2024
This manuscript introduces a novel calibration method for optical particle spectrometers (OPS) using statically mounted fibres, which simplifies the calibration process and reduces dependency on traditional aerosol-based techniques.
The method leverages Generalized Lorenz-Mie Theory (GLMT) to accurately calculate the scattering cross section of fibres, ensuring that the OPS provides reliable measurements across different conditions and settings.
Highlighted as both practical and versatile, this new technique offers significant improvements in OPS calibration, making it ideal for field applications and mass production of low-cost instruments.The paper is well-written and describes the new calibration method systematically, making it comprehensible for readers with knowledge of particle measurement using scattering technique. Indeed, the manuscript may not be easily understood by readers not familiar with the topic. If the author wishes to reach a broader audience, it would be beneficial to elaborate more on the fundamentals of measurement techniques and calibration.
The paper would greatly benefit if the author applied the new fibre calibration not only to the UCASS instrument but also demonstrates its effectiveness on another device, such as the OPC-N3 from Alphasense which uses a similar technique and is widely used in field application.
There is nothing to criticize about the writing style of the manuscript. However, the author should consider whether Figure 2 could be more effectively presented in colour, as the lines in the black and white plot are very close together, making it difficult for the reader to distinguish them.
A potential typographical error may be found in line 330. "However, The addition" should be replaced with "However, the addition".
Citation: https://doi.org/10.5194/amt-2024-55-RC1 -
RC2: 'Comment on amt-2024-55', Anonymous Referee #1, 02 Aug 2024
The manuscript “Calibration of Optical Particle Spectrometers Using Mounted Fibres” by Girdwood et al describes a new technique to calibrate OPSs – instead of the commonly used glass spheres the authors design a fibre mount and calibrate with that instead. This will be useful for calibration since it is much easier to use also in the field. The authors then compare the new technique to commonly used methods and show there is good agreement, using a UCASS instrument. The method with a static fibre could be also used on other instruments. Therefore, I think this manuscript is ideal for AMT and will be a useful addition after some minor changes.
My comments:
- Abbreviations in the abstract are not explained. In line 205 “ABS” is also not explained.
- Line 100 and 114: What exactly is “sufficiently” small?
- Line 135 delete “which”
- Line 180: The laser was modified to pulse with a gaussian profile. How easy/hard is that to do for an operator in the field? Would the instrument have to be removed from operation or not? How long would this procedure take?
- Fig 3 is mentioned after fig 4
- Line 207: “fixed distance” – what is it? Is it the same every time?
- Line 225: delete comma
- Line 236: Swap figure order such that 6 and 7 are mentioned in order.
- Figures 6/7: How exactly was the fit done, were only two/three data points used? Because the fit with two data points is not following these two points.
- Line 339: “mothodolody” (typo)
Citation: https://doi.org/10.5194/amt-2024-55-RC2
Data sets
Fibre Calibration Repository Jessica Girdwood https://github.com/wolkchen-cirrus/FibCalRepo
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