Germany Developed Short Wave Green Laser Underwater Cutting Technology

With the prominent energy issues in various countries around the world, the utilization and development of energy have become a hot topic, and the demand for renewable energy is constantly increasing. The existing underwater infrastructure is no longer sufficient and needs to be dismantled using appropriate modern technology. For example, in order to increase the power of offshore wind power plants, it is necessary to first dismantle the old steel frame structure that is currently below sea level and rebuild more advanced equipment.

Researchers at the Fraunhofer Institute of Materials and Beam Technology (IWS) have developed a shortwave green laser cutting method for seabed cutting, which has multiple advantages compared to commonly used technologies such as saws, automatic wire saws, and plasma cutting machines.

Researchers have stated that a short wave green laser with a power exceeding kilowatt level is a necessary condition for this technology to achieve cutting. In the future, shorter wavelength blue lasers can also be used to achieve this.

Short wave green laser cuts steel under seabed conditions. Source: Fraunhofer IWS

Since its inception, laser cutting technology has made significant progress and has been widely used in the manufacturing industry. However, infrared or other longwave lasers are usually used for cutting in dry environments, assisting in coaxial gas and beam cutting to remove molten metal generated during the cutting process. However, in the marine environment, the degree of absorption, reflection, and scattering of light of different wavelengths by seawater varies, and most lasers are dissipated after a short distance. Auxiliary gases also require complex pipeline systems.

Using green lasers with shorter wavelengths than most industrial lasers to penetrate seawater does not result in significant loss, reducing power loss. Therefore, this type of laser is also more suitable for marine environments. While existing green lasers operate in water, water can discharge the resulting melt from the incision under pressure. This abundant medium in the ocean can replace the cutting gas required in dry environments, thereby eliminating the need for natural gas pipelines.

In addition, gases and gas mixtures (such as air) used in laser cutting applications in dry environments need to be pre compressed, but water does not need to be compressed. Therefore, using seawater as the cutting medium, this technology can conveniently remove melt residues at the interface.

Patrick Herwig, project leader of the Fraunhofer IWS laser cutting team, stated that this method can also be applied to small underwater robots with laser accessories. Because underwater robots can operate underwater in complex environments with high risk, pollution, and even zero visibility, achieving more efficient cutting operations than existing automatic sawing and cutting machines.

On the other hand, laser underwater cutting technology is also more environmentally friendly. The dismantling team does not need to load new blades or other consumables onto the cutting laser, and this system does not generate waste or release hazardous substances into the atmosphere. This performance advantage is particularly important when dismantling old nuclear power plants. If gas is used as the cutting medium, radioactive waste is likely to be expelled from the water surface with bubbles.

At present, the technology is still in the laboratory testing stage. Next, researchers hope to develop the validation scale of the laboratory into a practical application system.

This article is compiled by Optoelectronics based on the content of photonics