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Course of ADVANCED MANUFACTURING PROCESSES Proff. Michele Monno – Barbara Previtali – Matteo Strano SURNAME NAME PERSONAL ID Exam 5rd March 2015 Exercise n. 1 – scientific article comprehension In order to locally improve mechanical proprieties of a component, a laser hardening treatment is required. To perform the heat treatment you have availed an ytterbium fiber laser with a Gaussian distribution which is unsuitable to ensure uniform material heat treatment . The delivery fiber is characterize d by a defined numerical aperture (NA) and a defined fiber core dimension (fiber). A possible solution is proposed in the article entitled: “ Microlens Laser Beam Homogenizer – From Theory to Application”. The method uses combination of two microlenses arrays (LA1, LA2) and a spherical lens (FL) which transform the energy distribution from Gaussian to a Flat-Top one. Referring to the scheme shown in Figure 1 and the technical data summarized in Table 1 you are asked to evaluate: Figure 1: Optical scheme Table 1: Technical Data Definition Symbol Value Unit Fiber diameter core 400 μm Numerical Aperture NA 0,25 Divergence after FL θout 0,35 rad Size of the flat-top spot Dspot 5 mm Diameter of the collimation lens DCL 25,4 mm D lens over D collimated beam DCL/Dbeam 2 - Beam flatness R 45 - 1. The divergence of the laser outgoing from the delivery fiber; =__________ rad 2. The collimated beam diameter Dbeam=___________mm 3. The collimation length fCL=__________mm 4. Considering the R value listed in Table 1, evaluate the pla pLA=__________ mm 5. Considering a punctual light source, placed at infinite distance in front of the first lens array, and you want to obtain a certain divergence out and a certain Dspot , evaluate fFL=__________ mm fLA=__________ mm 6. Considering an…