Exploring the deep sea – first-time LIBS measurement at 600 bar
10/15/2018

The measurement of elements with LIBS shall help to locate natural resources in a non-destructive way in the future. (Photo: GEOMAR (CC BY 4.0)

For the first time, a zinc sample was measured at 600 bar water pressure using the LIBS system developed by the LZH. Emission lines of zinc in the range between 465 and 485 nm at 0 bar (black) and at 600 bar (red). (Figure: LZH)

For the first time, scientists at the Laser Zentrum Hannover e.V. (LZH) have succeeded in measuring zinc samples at a pressure of 600 bar using laser-induced breakdown spectroscopy. They were able to show that the LIBS system developed at the LZH is suitable for use in the deep sea at water depths of up to 6,000 meters.

Locating mineral resources on the sea floor has so far been rather expensive. In order to reduce the costs, the LZH is working with eight other European partners to develop a laser-based, autonomous measuring system for underwater use by 2020. The system is supposed to detect samples, such as manganese nodules, and analyze their material composition directly on the deep sea ground.

Pressure chamber allows simulation of the deep sea
For this purpose, the scientists at the LZH are developing a system for laser-induced breakdown spectroscopy (LIBS) within the scope of the ROBUST project. In order to test the LIBS system developed by LZH under deep-sea conditions, a special pressure chamber was designed and manufactured. With the pressure chamber, a water depth of 6,500 meters can be simulated with a pressure of up to 650 bar. The chamber is suitable for both freshwater and saltwater and can thus simulate various application scenarios. Through a viewing window, the laser radiation enters the pressure chamber with the test sample to be analyzed.

LIBS is a non-contact and virtually non-destructive method of analyzing chemical elements. Solid materials, liquids and gases can be examined. The method is based on the generation and analysis of laser-induced plasma. Here, a high-energy laser beam is focused on the sample. The energy of the laser beam in the focal point is so high that plasma is created. The plasma in turn emits an element-specific radiation, which is measured with a spectroscope. The emission lines in the spectrum can be assigned to the chemical elements of the sample.

About ROBUST
The project "Robotic Subsea Exploration Technologies - ROBUST" (grant number: 690416) is funded by the European Union within the framework of the program "Horizon 2020".

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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, Transport and Digitalisation 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 sciences, application oriented research, and industry.