In recent years, laser cutting technology has significantly improved the processing efficiency with the increase in laser power of laser oscillators. Laser cutting needs the beam damper (ex. metal plate) to receive the laser beam passing through the products because of the safety and limitation product damage.

The conventional beam damper is almost a laser receiving system using the metal plate into cooling water. However, the damper cannot be used in recent high power laser oscillators because the surface of the damper melts. To solve receiving problem, we examined a technique to reduce high power and high power density of laser after cutting the object. In general, Water is not only highly absorbing effect of laser power, but also expected highly scattering effect from the difference in refractive index with air. Therefore, we thought that it would be possible to develop a beam damper suitable for high-efficiency laser processing by using water.

The beam damper is based on two phenomena with absorption and scattering by water. The damper by water has absorption by water curtain for reduction of laser power and scattering by water mist for reduction of power density. The absorption effect of the water curtain reduced the laser power by 94% and the scattering effect of the mist reduced the power density by 70% due to expand of the beam diameter. It was confirmed that new concept damper by using water significantly reduces power and power density by 80% and 98%. Therefore, its damper can be used for high power and high power density laser cutting process.

In the presentation, in addition to introducing the technology of the new concept damper system using water, we will report on the application to industry about combined with cutting processing.