## 1 Introduction  
The aim of the research was to design a non-contact method for obtaining a digital 3D model of a produced part, so as to measure the quality of production. This is an operation that has only been carried out using contact devices so far. These excel in their greater accuracy, but their measuring speed and ability to measure free-form products are low or insufficient [1, 2]. For this purpose, it was proposed to use optical systems for scanning, and then to compare the data obtained from actual manufactured products with those data from 3D digital models that were used for production [3, 4]. Another area of application of reverse engineering systems, such as scanning systems, is the documentation of historical objects and monuments that are part of the cultural heritage of human society [5]. As such, optical systems have come a long way during their development, and their accuracy, in which they have been lagging behind, is beginning to approach that of a coordinate measuring instrument [6, 7, 8]. The scope of their use is wide, mainly for operations with a large variety of products. Optical systems can shorten the time of measurement, as well as the evaluation of measured data, which significantly streamlines the work of the employees of the relevant department. A convincing argument for the implementation of scanning devices is also the cost saving, simplification and acceleration of the quality control process. Above all, there is an overall increase in the level of quality [9, 10, 11]. The development of technologies in reverse engineering opens new horizons in the areas of quality assurance and control. Great progress is being made with non-contact devices, the accuracy of which is beginning to approach that of conventional contact coordinate measuring instruments. One of their main advantages is the scanning speed; the systems can scan the measured object several times faster, which ultimately meansincreased productivity and the ability to control a larger number of products. Another advantage of contactless scanners is the easier and faster processing, when comparing the measured data with a CAD model, which, again, brings an increase in the productivity of quality personnel, scope to reduce labor costs, and extends quality control functions to larger production volumes [12; 13; 14]. The basic concept of the reverse engineering process is shown in Figure 1.  
The procurement of such technology for scanning real objects is demanding, in terms of finances and the number of alternatives available on the market. Any decision of one expert is only subjective, and may not take into account all the aspects necessary for a proper evaluation of the characteristics of the available equipment and the selection of the most appropriate solution [15]. Therefore, it is appropriate to use scientific methods to assess the selected factors, preferably with the help of experts from several fields, who have a different perspective on evaluation [16]. This article deals with the system of selecting a suitable scanning device for reverse engineering using the pairwise comparison method and AHP. Pairwise comparison is a scientific method of analyzing a number of different objects or subjects to determine if they are significantly different from one another. There are several different methods, which are based on the same principle--assessing several variants of solving a given problem according to the selected criteria, and determining the order of these variants. The individual methods differ according to how the so-called weight of the individual criteria and the degree to which the individual variants of the solution meet the selected criteria are numerically evaluated [17; 18]. Figure 1: Reverse engineering process—basic concept. DMM (decision matrix method) is considered to be a basic method (it can have several solution variants) [19; 20; 21].