Analysis of Laser Beam Shaping Properties Development of Novel Laser Beam Shaping Optics and Its Applications to Materials Processing (Rept. 1)

• Published in: QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY Vol. 12; no. 2; pp. 207 - 212
• Main Authors: Maruo, Hiroshi, Miyamoto, Isamu
• Format: Journal Article
• Language: Japanese
• Published: JAPAN WELDING SOCIETY 05.05.1994
• Subjects: beam splitting; CO2 laser; geometrical optics; interference; linear-polarization; physical optics; reflectivity; shaping efficiency; surface modification
• ISSN: 0288-4771; 2434-8252
• DOI: 10.2207/qjjws.12.207

A novel laser beam shaping optics was developed, which can provide high shaping efficiency and high absorptivity to base metal. The optics consists of two cylindrical lenses, a pair of flat mirrors and a spherical lens. Shaping properties in terms of intensity distribution and shaping efficiency were analyzed on the basis of the geometrical and the physical optics where spatical intensity distribution and angular reflectivity of complex refractive index were taken into consideration. CO2 laser beam was shaped into a spot with uniform intensity distribution along y-axis with original intensity distribution along x-axis at variable aspect ratios, Dy/Dx, where Dx and Dy are spot size in the x-and y-axes, respectively. Shaping efficiency for different laser modes was determined as a function of angle φ between the polarization vector and the normal of the flat mirrors, and satisfactory agreement between experimental and theoretical values was obtained; negligible shaping loss was attained at φ=90 degrees in contrast to 40% of shaping loss at φ=0. Single CO2 laser beam was demonstrated to be split into 19 beam spots by utilizing the interference of the laser beam; the number of the spot can be easily changed by changing the ratio of length and distance of the flat mirrors.