A device for digital holographic powder layer inspection based on multi-wave holography

Abstract

The invention relates to the field of information and communication technologies, digital holography and optical control of surfaces and can be used in additive manufacturing systems, including selective laser melting (SLM) and selective laser sintering (SLS) systems, as well as in other technical systems that require restoration of the spatial relief of the surface and the formation of control actions based on the results of digital analysis. A device for digital holographic control of a powder layer based on multi-wave holography is proposed, containing spatially distributed laser sources of coherent radiation of various wavelengths, a holographic optical system for forming an asymmetric reference wave system, a light-sensitive matrix for recording interference images, a computing module for digital data processing and a software analysis module. A distinctive feature of the device is the use of an asymmetric architecture for generating a reference wave, which includes a dominant reference wave of increased intensity and a set of auxiliary reference waves of lower intensity, the parameters of which are selected based on the condition of matching the dynamic range of the photosensitive matrix. The device provides multi-position multi-wave coherent irradiation of the surface under study, recording a set of interference structures on a single light-sensitive matrix, digital processing of interference information flows, restoration of the spatial relief of the surface by means of phase reconstruction, identification of defective zones and the formation of a digital surface correction map. The technical result consists of increasing the accuracy and reliability of the reconstruction of the spatial microrelief of the surface, increasing the resistance to optical noise and speckle inhomogeneities, expanding the range of measured surface heights, reducing the computational complexity of the analysis, reducing the time for data processing and reducing the delay in making control decisions in real time.