3D Holographic Interrogation of Additive Manufacturing
Abstract
Additive manufacturing (AM) has become very popular and useful in many areas such as in the medical industry, automotive industry, computer science, engineering, etc. 3D printing can be used to manufacture things which could be as simple as a toy car to complicated parts of an aircraft. At the Intelligent Optics Lab (IOL) in Electro-Optics and Photonics (EOP) at the University of Dayton (UD), there is a new facility to do 3D manufacturing of objects starting from raw material in a metallic powder bed using a high power laser beam composed from coherent combination oflaser beams. Besides materials savings, this also gives the added flexibility of changing the material properties during the 3D printing process.As AM is poised for growth and innovations, it faces barriers of lack of in-process metrology and control to advance into wider industry applications. Scanning electron microscopy and atomic force microscopy are two common techniques which can be used to map various surface profiles. Although they are reliable and accurate techniques, it is not convenient to use them for in-situ monitoring. Additionally, using these techniques can be also expensive. Very recently, (digital) holography has been implemented into automotive production facility for parts inspection.Holography is an established technique to record and visualize 3D information of an object. In digital holography (DH), the hologram, or interference pattern between reflected/scattered/transmitted light from an object and a reference, is recorded on a CCD camera and reconstructed digitally on a computer using numerical techniques which mimic Fresnel diffraction during propagation. Reconstruction retrieves both amplitude and phase/depth information of the object, thereby revealing its 3D profile.At the Holography and Metamaterials (HaM) labs in EOP at UD, we have extensive experience in using DH, digital holographic topography and tomography, and multi-wavelength DH (MWDH) to perform 3D mapping of surface profiles starting from hundreds of nanometers to tens of centimeters, calculate the volumes of 3D structures, etc. In this work, we propose to interrogate the entire AM processing area using MDWH with spatial heterodyning, starting from the powder bed to the finished product, including every deposited layer during AM and project 3D renditions of the surface(s). In the process, the volume of the object fabricated through AM can also be obtained. Starting from interrogation of surfaces of approximately 5 mm x 5 mm to optimize the recording wavelengths, the process will be extended to larger areas e.g., 2.5 cm x 2.5 cm through scanning the CCD, and finally to the entire 15 cm x 15 cm surface of the powder bed through additional beam scanning. The last two steps will be incorporated into the setup in IOL for in-situ monitoring of AM. At every step, indigenous GUIs will be developed to automate the process of hologram recording and reconstruction, scanning, and numerical stitching to find the overall 3D image, while optimizing the efficiency of the process.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 27, 2018
- Source ID
- N000141812564
Entities
People
- Partha Banerjee
Organizations
- Office of Naval Research
- United States Navy
- University of Dayton