Sources and Detectors group ensures U. S. Military gas mask performance

CBRN warfare is the use of chemical, biological, radiological, and nuclear weapons in combat. CBRN weapons are designed to cause mass casualties and disruption. While their use in warfare is limited under the Geneva conventions, both state and non-state actors continue to pose CBRNE threats to U. S. forces.

Gas masks are the critical element in every soldier’s counter CBRNE kit. As the first item donned during an attack, soldiers are expected to be masked within 9 seconds of an alert. And, just as the soldier is routinely tested for their ability to fully don a mask within allotted time, their equipment must also undergo routine evaluation for filtration efficiency and gas-tightness. That test system relies on optical power instrument calibrations provided by the Sources and Detectors Group.

All gases absorb infrared radiation at a unique combination of wavelengths, creating an “optical fingerprint”. By passing infrared light through a test gas (a gas that simulates the optical characteristics of a poisonous gas, without the poison), and comparing the light before and after it passes through the gas mask, the change in gas concentration can be measured. If the gas mask is functioning properly, the IR light passing through the test gas after the mask should show a significant reduction in absorption (i.e., the test gas concentration should be lower, passing more light). Leak detection is accomplished in much the same way. When a test gas enters through a leak, the air in the mask exhibits an increased infrared absorption signature compared to the desired atmosphere, permitting detection of a leak. Accuracy in the optical measurements is therefore key to reliable CBRN protection.

Within the United States, NIST’s Sources and Detectors Group offers the lowest uncertainty calibrations at the power and wavelength needed for the detectors used in the gas mask testing systems. This is the result of ongoing engineering and research in optical metrology for DoD and other applications. The facility supporting gas mask test equipment, amongst other DoD and Commercial customer calibrations, has recently (Jan 2025) passed the first functional test of the rebuilt primary standard [1] used to provide these calibrations. By rebuilding the instrument, we were able to achieve system improvements that decreased noise and calibration uncertainty.

Through its customer driven calibration services, NIST provides this, and many other tailored services to meet any DoD need. This ensures the highest quality DoD standards for precision, safety, and technological advancements. With its continued improvements, the Sources and Detectors group at NIST plays a crucial role now, and in the future, protecting U.S. Warfighters and bolstering safety technology on the field.

[1] A. Vaskuri, et. al. “High-accuracy room temperature planar absolute radiometer based on vertically aligned carbon nanotubes”, Optics Express 29, 14, (2021). https://doi.org/10.1364/OE.427597