Defusing World War bombs more safely with laser radiation

With a laser-based process, the deactivation of unexploded bombs is to become safer. (Photo: LZH)

Aim of the research project: Notching a bomb with the laser so that it can be defused safely and deliberately by deflagration. (Photo: LZH)

Unexploded bombs are and will remain a serious threat to civil security in many parts of the world. To be able to deactivate these bombs more safely in the future, the Laser Zentrum Hannover e.V. (LZH) is working on a laser-based defusing together with the LASER on Demand GmbH and the Kampfmittelräumdienst Hamburg (KRD). At the Hannover Messe 2018 from April 23rd to 27th, the LZH will be showcasing processed bomb shells at the Pavilion of the State of Lower Saxony (hall 2, stand A08).

The challenges and dangers of conventional defusing methods are enormous and still highly topical: The amount of weapons hidden underground in Germany is difficult to predict, but according to KRD estimates, about 60,000 tons are still in the ground. During the defusing process there is an extremely high risk of unwanted detonation, especially in complex ignition systems. Often blowing up the dud remains as a last resort.

Weakening of the casing takes explosive power
In the DEFLAG project, the project partners LZH and LASER on Demand are working on a procedure to defuse the bombs by targeted deflagration. In contrast to a detonation, a lower pressure wave is created during deflagration and the explosive is converted only to a small extent. The project partners notch the bomb casing with laser radiation and trigger the deflagration in a second step. In cooperation with the KRD, a field-compatible and automated processing platform is to be created – to safely defuse even dangerous unexploded bombs.

Mobile, safe and reliable
Essential for the project is not to exceed a critical temperature limit on the underside of the material, to drive out material from the ablation groove and to ensure process mobility. Scientists at the LZH have so far been able to notch up to 25 mm thick steel sheets using a combined melting and flame removal process. In doing so, they achieve an ablation depth of up to 16 mm with an external gas supply. At the Hannover Messe, they show processed bomb casings and material samples.

The LZH will show this exhibit also at the LASYS in Stuttgart from June 5th to 7th, 2018.

About the project
The DEFLAG project "Safe Deflagration of Duds by Laser Technology" is being funded by the German Federal Ministry of Education and Research within the scope of the Federal Administrations "Research for Civil Security 2012-2017" program. The fire department Hamburg / bomb disposal team is the Associated Partner.

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Laser Zentrum Hannover e.V.  (LZH)

As an independent, non-profit research institute, the Laser Zentrum Hannover e.V. (LZH) stands for innovative research, development and consulting. The LZH is supported by the Lower Saxony Ministry for Economics, Labour and Transport and is dedicated to the selfless promotion of applied research in the field of photonics and laser technology. Founded in 1986, over 170 employees are now working for the LZH.

The focus of the LZH lies on the fields of optical components and systems, optical production technologies, and biomedical photonics. Interdisciplinary cooperation between natural scientists and mechanical engineers makes innovative approaches to challenges from the most different areas possible: from the development of components for specific laser systems to process developments for the most diverse laser applications, for example for medical technology or lightweight construction in the automotive sector. Nineteen spin off companies have emerged from the LZH up to now. Thus, the LZH has created a strong transfer between fundamental science, application oriented research, and industry.