An Enclosed variable focusing lens for remote welding

Ryoichi Kuwano,Yukitoshi Otani,Yuta Okane,Sho Morita,Tsuyoshi Tokunaga

doi:10.1051/matecconf/20153207003

Abstract

In this study, a variable focusing lens with a driving mechanism was developed. The surface curvature of the lens is formed via the interaction of elastic film tension and liquid pressure generated by compression of a bellows, which enables the focal length to be changed. This paper discusses the optical characteristics of the lens system. The focal length range is 250 - 750 mm with beam diameters of 0.3 mm - 0.9 mm, respectively, when a YAG laser is irradiated. In the study, the lens system was applied to laser beam welding of mild-steel sheet with a thickness of 0.5 mm for 3,000 shots of laser irradiation at a peak power of 4.7 kW and a duration of 10 ms.

Highlights

The authors previously proposed a liquid pressurecontrolled variable focal lens [1, 2] whose focal length adjustability allows the control of laser energy in the optical axis direction
Remote welding using high-power lasers with a large focal length has been developed [9] in conjunction with the availability of high-power laser beam sources featuring high beam quality since the 1990s
Variable focal lenses are suitable for such application because the remote welding process requires frequent adjustment of positional focus

Summary

Introduction

The authors previously proposed a liquid pressurecontrolled variable focal lens [1, 2] whose focal length adjustability allows the control of laser energy in the optical axis direction. Other variable focal lenses have been proposed [3 – 8]. Remote welding using high-power lasers with a large focal length has been developed [9] in conjunction with the availability of high-power laser beam sources featuring high beam quality since the 1990s. Variable focal lenses are suitable for such application because the remote welding process requires frequent adjustment of positional focus. The optical characteristics of the proposed lens were compared with those of a commercially available plano-convex lens, and the use of an optical actuator for lap welding with a YAG laser was demonstrated for related application

Principles and mechanisms of variable focus

Experimental results

Conclusion