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A Unique Split Laser System for Environmental Monitoring

Date Posted
USPN 7,421,166; USPN 8,786,840; USPN 8,934,511; USPN 9,297,696; USPN 9,548,585


Researchers at the U.S. Department of Energy’s National Energy Technology Laboratory (NETL) have developed a novel split laser system for in situ environmental monitoring via Laser Induced Breakdown Spectroscopy (LIBS) or Raman analysis.  The design features fiber-coupled, optically-pumped, passively Q-switched lasers that are small, portable, low cost and robust enough for even downhole applications.  The technology can be used in a wide array of applications, including, but not limited to, carbon dioxide (CO2) monitoring for CO2 sequestration, oil and gas monitoring, and water analysis (groundwater and municipal systems).  The technology is available for licensing and/or further collaborative research with NETL.

Proof of concept experimentation has been completed. NETL researchers are continuing to design miniaturized lasers and optical delivery systems to allow further size and cost reductions. The researchers have identified the need to complete and demonstrate both single point and multipoint measurement prototypes.  The results would further validate the technology and expedite its deployment to the private sector. 


Environmental monitoring, i.e., the assessment of air,  water and soil quality, is highly important to oil and gas exploration companies, landowners, regulatory agencies, municipalities and any organization measuring emissions and pollutants.  The majority of monitoring technologies, however, are expensive and labor intensive, often requiring sample collection and preparation (i.e., external lab analysis) which can dramatically alter the sample and its inherent components.  Of those technologies that do allow for in situ analysis, few are amenable to measurements under harsh conditions, such as high temperature and/or pressure.

Laser Induced Breakdown Spectroscopy (LIBS), an atomic emission spectroscopy, offers solutions to the drawbacks of conventional environmental monitoring technologies.  It provides rapid and relatively simple qualitative and quantitative elemental analysis.  Significantly, this analysis can be accomplished without the need for sample collection or preparation. Moreover, LIBS can be applied to in situ measurements of gases, liquids and solids, making it amenable to the monitoring of air, water and soil.  The majority of available LIBS systems, however, are large and complex, employing aboveground, laboratory-scale lasers.  Furthermore, the design of current systems and the complexity of their components do not allow for monitoring under extreme conditions, such as high temperature and pressure.

NETL researchers have designed a LIBS system fully adaptable to field use and capable of measurements in harsh environments.  The system has been designed to be portable, with a minimal number of optical components, no moving parts and no electrical connections, which should translate into far lower production costs than competitive devices.  In addition, unlike competing LIBS systems which employ actively Q-switched lasers, NETL’s system utilizes a passively-switched laser, providing the same degree of precision timing as the actively-switched output with fewer components and a lower cost laser system. The NETL system also employs a unique split laser design.  Conventional LIBS analysis requires complete laser systems to deliver a high peak pulse to the sample, incompatible with the use of optical fibers which are ideal for at-a-distance monitoring.  To avoid fiber optic damage, NETL’s system employs a remotely-positioned laser diode pump capable of generating a peak power of only a few hundred watts as compared to the megawatts produced by conventional systems.  The low peak pulse is delivered via a fiber optic cable to a remotely-located solid state laser where the high peak pulse necessary for analysis is produced. Significantly, this unique dual laser arrangement coupled with solid state optics permits monitoring of even severe downhole environments while avoiding system damage.

The split laser design also provides for multipoint analysis, allowing multiple lasers to be distributed over a broad area, ideal for applications such as the detection of CO2 leakage from an injection basin.  Adding to the system’s flexibility, with few modifications the same system can also be used to provide output for Raman analysis, permitting the identification of organic compounds such as methane.  Thus, one system can be designed to be used for both LIBS and Raman investigations.  For example, the system can be used above ground or downhole to directly monitor CH4 via Raman analysis and detect changes in groundwater ions via LIBS.

  • Rapid, sensitive, in situ measurements even under extreme conditions (I.e., high temperatures and pressures)
  • Flexibility of single or multi-point monitoring using either LIBS or Raman spectroscopy
  • Minimal complexity with low fabrication costs
  • Assessment of solids, liquids and gases in a broad array of applications (see below)

Long-term CO2 sequestration monitoring

  • Obtain surface, near-surface and subsurface measurements of CO2 post injection into geologic formations to validate storage and detect leakage
  • CO2 can be measured directly or indirectly via monitoring changes in groundwater ion concentrations


  • Assess downhole fluid chemistry before and after hydrofracturing
  • Monitor effects on groundwater via elemental LIBS
  • Detect natural gas reservoirs using downhole Raman analysis, thereby optimizing well production and reducing drilling costs

Municipal water treatment and filtration systems

  • Provide on-line quantitative measurements of impurities and contaminants
  • Monitor key operational parameters to improve productivity and enhance cost controls

Offshore Oil and Gas Industry

  • Identify potential fossil fuel reservoirs
  • Monitor impact on marine environment from initial exploration, through production to decommissioning
  • Provide analysis of produced water prior to discharge/disposal

Pollution/Contaminant Monitoring and Remediation

  • Measurement of ground water quality, air quality (indoor and outdoor) and soil composition

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