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Enhancing oil and gas pipeline sensing with SWIR optical filters

Optical filters are essential in oil and gas pipeline monitoring sensors

Optical filters are essential in oil and gas pipeline monitoring sensors, which often operate in the short wave infrared (SWIR) range (Credit: MVelishchuk/

In the oil and gas industry, sensors are used in a number of processes to help ensure safety, efficiency, and productivity. Some of the most common uses include well monitoring; environmental monitoring; safety monitoring; remote monitoring; production; and pipeline monitoring. This article focuses on the latter, and how Chroma Technology was able to bring its 20+ years of experience as supplier of highly precise optical filters to this application.

Optical filters are a key component in helping sensors allow for the selective detection of specific wavelengths of light corresponding to the chemical signatures of contaminants present in the oil or gas flow within the pipeline. To optimise the sensor’s performance for different types of contaminants and operating conditions, filters can be customised according to the unique requirements of the application. In the case of pipeline monitoring sensors, which often operate in the short wave infrared (SWIR) range, filters are essential for isolating and detecting the desired wavelengths associated with target contaminants.

For one company developing a pipeline monitoring sensor, the customisation and SWIR operation were particularly critical. They required optical filters with specific bandwidths, cut-ons, and cut-offs tailored to precise wavelengths corresponding to the chemical signatures of contaminants. In addition, the compact design of the sensor posed technical challenges, and required highly optimised optical coatings to ensure the durability needed against challenging environmental factors. In the case of the pipeline sensor, the primary concern was in developing a filter which could withstand the physical vibrations and significant temperature variations present in the field.. The customer needed a reliable partner, capable of providing custom solutions that met these stringent technical requirements.

SWIR optical filters from machine vision to oil and gas monitoring

Chroma Technology was ideally placed to help, having significantly invested into its range of SWIR filters for a variety of industry applications. John Atkinson, Principal Product Engineer at Chroma Technology explains: “I think we make some of the best SWIR optical filters in the industry, and that's what the customer required. Our catalogue product was more geared toward machine vision and remote sensing, and while it has applications in a wide range of industries, we didn’t think that a potential customer in the oil and gas industry would necessarily be knocking on our door. But, it allowed us to use our existing technology in a new market.”

To meet the brief, the team at Chroma Technology collaborated closely with the customer, offering suggestions that, on occasion, diverted from the original product design in order to optimise its performance. Atkinson explains: “They had a basic idea of how it would work. They started off by asking for filters with specific bandwidths to line up precisely with their ideal wavelengths, based on the chemical signature of the contaminants. In practice, the mechanical situation, the beam shape and the makeup of the instrument as it was constituted in the beginning required some pretty challenging optical coatings. They worked with us to optimise their system and actually changed their design as we presented different spectral solutions.”

The solution also had to take into account more than the optical performance alone, says Atkinson. “There was also a thermal factor because of the temperature change, and there can be vibration present, so the sputtered filters needed to be highly durable, as ours are. It was a given that we could provide them with a very robust product to meet these challenges.”

Close collaboration for highly optimised results

The companies also worked together to overcome the challenges associated with such a compact device. Says Atkinson: “The way the light path had to travel through the instrument, created a scenario where the interference filters, which are subject to the angle of incidence, had to be highly tuned and optimised to to allow every possible photon to either get through or be reflected. We also had to contend with the flatness of some of the optics, such that the beam was not distorted, because that would have lost a few more photons. So, it was highly optimised.”

The collaborative efforts went both ways, as Almut Bailly, Account Manager at Chroma Technology explains: “The collaboration was very special. They were so responsive and open to any kind of discussion, and it proved that working together closely, listening to the details that the customer wants, and discussing the options is the best way to find the optimal solution.”

Chroma Technology provided optical filters offering very high transmission, deep blocking, steep transitions, and very precise band placement in order to boost the signal to noise, which was necessary to find such low levels of contaminants. And it didn’t end with the closing of the sales order, the customer actually returned when they required another filter solution. What’s more, the client got back in touch with the team to fill them in on the results.

Says Bailly: “This customer called a meeting with us specifically to let us know how happy they were. They gave us a whole summary presentation on the tests that they had done with the instrument, and showed us the results, including the data demonstrating that the instrument worked exactly as required.”

Find out more about Chroma Technology’s range of SWIR filters for multiple applications. 


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SWIR, Energy industry

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