## 1 Introduction  
Additive manufacturing processes [1] build up a component through a continuous mass input. Typical processes are the FDM process (fused deposition modeling) [2], which is common for polymers, the LPBF process (laser powder bed fusion) [3] or the LMD process (laser metal deposition) [4]. All these processes have in common high geometric flexibility due to free-form modeling without a mold. In the field of additive processes for metals, potentials for new material concepts [5, 6] arise from the use of the comparatively high cooling rates [7, 8] in the range of \(10^{5}\)-\(10^{6}\) K/s for the LPBF process [9]. However, process parameters that minimize defects in the printed component [10] must be determined at great expense for each new material. The search for optimized and robust parameter sets [11, 12] is a time-consuming process.  
Defects in additive manufacturing [13] result, on the one hand, from the material properties and properties of the powder (e.g., bulk density, flowability, particle size) and, on the other hand, from the process conditions, with particular emphasis on the importance of thermal conditions [7]. While for a given material the material properties and the resulting solidification kinetics are fixed, the various parameters of typical LPBF systems offer a wide range of possible process conditions. Two essential parameters are the scan speed \(v_{S}\) at which the laser moves over the powder bed and the laser power \(P_{L}\) (Figure 1).  
With the layer thickness \(l_{Z}\) and the hatch distance \(h_{S}\), the volume energy density is obtained.  
\[E_{V}=\frac{P_{L}}{v_{S}\cdot h_{S}\cdot l_{Z}} \tag{1}\]  
If the chosen volume energy density is too low, not all of the particles can be completely melted and irregular pores are formed [14], which often may still contain loose particles. If, on the other hand, a volume energy density that is too high is selected, strong evaporation of the material in the keyhole will occur. As a result of the high solidification rate, the gas formed cannot be released from the keyhole entirely and remains as spherical pores in the solidified material [8]. Cracks [15] typically occur due to stresses caused by high local temperature gradients, phase transformation or shrinkage. Minimizing such defects is of great importance since defects will decrease mechanical properties [16] or lead to material failure [17].  
While the average porosity of a sample may be determined by the Archimedes method, a determination of the shape of porosity to determine its origin requires image-based methods [18]. These include two-dimensional methods such as classic metallography, or may also feature three-dimensional methods such as micro tomography [19]. While three-dimensional methods offer the possibility to analyze volumetrics, their resolution is still lower than classical light microscopy or electron microscopy. Light microscopy allows the determination of spatial distributions of porosity in a cross-section, making it a very versatile and automated tool. The detailed analysis of pore size distribution has been shown to be an important quality measure for additively manufactured parts [20].  
While many studies search for the porosity minimum from a combinatorial variation of scan speed and laser power [11; 21], this work includes the defect type and pore size distribution to find good processing conditions for the ferritin steel 410L. These analyses are based on our open source framework \"PoreAnalyzer\" that is easily adaptable for custom applications.