Understanding high-power fiber-optic laser beam delivery

Abstract

Fiber-optic beam delivery is commonly used on industrial laser systems. This article examines the conditions for the optimal propagation of high power beams through optical fibers. Beam quality effects by step and gradient index fibers of different lengths are considered. The differences between the diverging beam from a fiber and the beam at focus and on the fiber face are illustrated. Estimates are provided of the worst-case beam quality to be expected from fibers. Guidelines are also provided for the selection of beam delivery components based on the limitations of the optical system and the tasks to be performed.

Utilization of Fiber Optics for Remote Sensing by Laser-Induced Plasma Spectroscopy (LIPS)

“…Hence, all ® bers were cut by a conventional diamond tool (Infocut, Polytec, Waldbronn, Germany) and subsequently polished (FIBRMET, BuÈ hler, DuÈ sseldorf, Germany); surface quality was controlled by m eans of a microscope (403 magni® cation). As has been noted for a ® ber polishing process with CO 2 lasers 15,16 described earlier in the literature, we frequently obser ved a pattern of laser conditioning/cleaning for ® bers used for the ® rst time: after an initial breakdown on the ® ber input endface, a breakdown was not observed later, even for higher transmitted laser pulse powers. However, m icroscopic analysis established no evidence of ® ber damage.…”

Validation Data and Model Development for Fuel Assembly Response to Seismic Loads

“…24. Definition of measurement region-(a) top view portraying vertical plane alignment with center of rod 2, measurement region shown in solid red line (b) front view, vertical PIV plane measurement region shown in red outline, processed PIV FOV shown in black dashed line prior to shaking, lower boundary 15 mm above spacer grid 2…”

“…24. Time series for 39,920 PIV fields, from top (a) displacement of rod wall extracted from PIV images, (b) instantaneous axial velocity $\mathcal{W}$ in grey with 6 Hz low pass filtered data in colored lines over-imposed at 3 points in channel; red = 3 mm, green = 7 mm, blue = 10 mm from the channel wall, and (c) filtered data for 3 points with RMS velocities in black for each respective point.From Fig.…”