## 4 Conclusions  
In the presented study, a new correction method for the beam-steering effect is presented. The beam-steering effect is a systematic error, occurring in laser diffraction measurements of spray droplet sizes, generated by pneumatic atomization or when parts of the liquid phase evaporate in the measurement zone. Due to this measurement error, apparent large droplets are detected, leading to a misbalance in the measured size distributions. This misbalance is problematic if the results of the performed droplet size measurements are used in the design of subsequent process steps which are over-proportionally influenced by large droplets.  
The commonly used method for correction of the beam-steering effect is based on a reduction of the measurement range of the used laser diffraction device by detector deactivation. This method is applicable when real droplet sizes are clearly smaller than apparent droplet sizes, caused by the beam-steering effect. If the real and apparent parts of the distribution overlap, some detectors cannot be deactivated without cutting the real droplet size distribution. As a consequence, an overestimation of large droplets has to be accepted when detector deactivation is applied. However, the method of detector deactivation shows excellent results when real and apparent droplet sizes are completely separated. Therefore, this method can still be used safely in the case of separated distribution parts.  
The presented correction method is based on a multimodal log-normal fit of measured distributions. The modality, representing the largest droplets was assumed to be caused by the beam-steering effect. This assumption was verified by measurements without liquid droplets. The real size distribution is calculated by splitting the beam-steering modality from the measured distribution.  
The new method was applied to previously published droplet size measurements, using an internal mixing ACLR atomizer, which had not yet been analyzed according to the largest droplets of the distribution. In measurements with overlapping real and apparent size distributions, the new method clearly reduced the overestimation of large droplets in measured size distributions, compared to results of the method of detector deactivation. The method can be applied to all tested measurement scenarios and seems to be valid for all spray droplet size measurements by laser diffraction. Therefore, the new modification method is recommended for use in all laser diffraction measurements of spray droplets, in which the beam-steering effect occurs.  
Conceptualization, M.O.W. and V.G.; Methodology, M.O.W.; Validation, M.O.W., H.P.K. and V.G.; Investigation, M.O.W.; Writing-Original Draft Preparation, M.O.W.; Writing-Review & Editing, H.P.K. and V.G.; Visualization, M.O.W.; Funding Acquisition, H.P.K. and V.G.  
The IGF Project AiF 18299 N of the FEI was supported via AiF within the programme for promoting the Industrial Collective Research (IGF) of the German Ministry of Economic Affairs and Energy (BMWi), based on a resolution of the German Parliament.  
We acknowledge support by Deutsche Forschungsgemeinschaft and Open Access Publishing Fund of Karlsruhe Institute of Technology. The authors further express their thanks to [PERSON], [PERSON], and [PERSON] for experimental support.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.