Image Credit: Maryna Stamatova/Shutterstock.com
Recent years have seen a growing interest in laser-based trace gas sensor technology. This can be mostly attributed to the growing concern over global warming. With governments, organizations, and citizens worldwide becoming more aware of the damaging effects of climate change, and the increased motivation to take action against the detrimental impact on our environment, all effective ways of reducing emissions are being explored and efforts are being made to improve them.
Laser-based trace gas sensor technology has already established itself as an effective method for detecting greenhouse gases such as carbon dioxide and methane. Being able to reliably detect and measure these substances is an important step in facilitating their reduction. The ability to quantify the levels of greenhouses gases in the air, and also being able to measure how they are changing are important elements of strategies that work to reduce emissions.
What is Laser-Based Trace Gas Sensor Technology?
While there are a number of different ways that lasers can be used to detect gas, they all work on the same basic principles. First, a laser induces the vibration of the gas molecules present, causing a dip in the detected light wavelength. This will only happen when the light wavelength is the right length for the gas molecule to absorb. Different gases absorb slightly different wavelengths and therefore the presence of specific types of gas molecules can be identified and measured.
Increasing the Sensitivity of Laser-Based Trace Gas Sensors
Laser-based trace gas sensors are already recognized as being more sensitive than alternative gas sensing technologies. However, scientists are continuing to work on improving this sensitivity.
The easiest way to increase the sensitivity of this technique is by lengthening the optical path that the laser light passes through, although there are limits to how much this can be increased by before it becomes ineffective.
Next, a multiparty cell can be used to increase sensitivity. Here, the light from the laser enters a gas cell where it bounces off the reflective mirrors inside it and exits the cell where a detector senses it. This allows for a longer light path to be achieved without increasing the size of the equipment.
Perhaps the most useful method that has been the focus of much research in recent years is the use of an optical cavity to increase sensitivity. This technique can be established in many ways, all of which utilize optical resonance by employing highly reflective mirrors, and traps the light from the laser within a cell.
Applications of Laser-Based Gas Sensors
As discussed above, the monitoring and measuring of greenhouse gases is the main application of this technology. These sensors are already being used in numerous ways in a variety of industries to help generate quick and accurate readings of certain greenhouse gases to assist in their regulation. They are perhaps the most popular type of gas sensor in this application for their ease of use and relatively low cost.
In addition, numerous industries rely on these types of sensors to ensure the safety of the workplace. For example, these gas detectors can be used in environments that work with gas to alert workers to even the smallest levels of a hazardous gas leak. They have become particularly prevalent in their use for detecting dangerous gases such as hydrogen fluoride and hydrogen sulfide.
They are also heavily relied upon by the oil and coal industries to detect methane build-ups. Gas companies also employ their use in investigating gas leaks. The detectors are available as portable units, so in this situation they can be placed in vehicles, measuring gas levels as the driver moves along the gas system, attempting to locate the source of the leak.
References and Further Reading