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What are SWIR, MWIR, and LWIR – And what do they mean?

Overview

Infrared Thermography operates through the infrared region beyond the visible light spectrum. Everything within the infrared wavelength radiates energy that can be visually captured through a thermal imaging device. Each wavelength in the infrared spectrum emits a certain amount of radiation that can be transmitted and captured through a thermal imager operating in that wave band.

In infrared thermography, there are three wavelengths that can be broken down even further to specific wavelength ranges. The three wavelengths are: Short Wavelength Infrared (SWIR), Medium Wavelength Infrared (MWIR), and Long Wavelength Infrared (LWIR). 

All Thermal imaging devices operating on the infrared wavelength are, ‘imagers‘ that we commonly refer to as ‘cameras’, however they are really sensors that can detect radiated heat.

Short Wavelength Infrared (SWIR)

Short Wavelength Infrared, or SWIR, is typically defined as the 0.9 – 1.7 μm wavelength range.

SWIR cameras generally have limited benefits compared to their counterparts (MWIR/LWIR).

These imagers have the ability to capture clear detail through smog, clouds, and haze. SWIR cameras are the only wavelength technology that can penetrate cloud coverage and capture a clear image.

Short Wavelength cameras are used in daytime starlight imagery because of SWIR’s ability to capture reflected light with peak solar illumination.

SWIR Inspection Applications

  • Solar Cell
  • Food/Produce
  • Circuit Board
  • Counterfeit

SWIR by FLIR

Handheld Camera

A6260
Research and development camera operating on the 0.9 to 1.7 µm waveband. With synchronization controls allowing for high-speed pictures to be taken with integration timings.

Camera core

Tau
Used for: hyperspectral instrumentation, silicon inspection, electro-optical payloads, art restoration, and portable imaging
  

Middle Wavelength Infrared (MWIR)

Middle Wave cameras are used as detection systems for gas leaks, some of which are completely invisible to the human eye!

MWIR is typically defined as the 3.0 – 5.0 μm wavelength range.

Knowing the difference between Middle Wavelength Infrared and Long Wavelength Infrared is extremely important as MWIR and LWIR devices are capturing separate waves that are useful for many different reasons. 

Optical Gas Imaging

FLIR’s OGI technology uses MWIR cameras to detect certain gasses like Methane, Propane, Ethanol, Sulfur Hexafluoride, and more.

Note: It is important to know which OGI camera is right for you, as OGI cameras operate on a very limited wavelength where the gas you may need for your detection services are not visible.

MWIR cameras are important when detecting gas leaks that are invisible to the human eye. These cameras are also used when detail is more important than exact temperature. Allowing the camera to be used as a perfect tool for airport perimeter security, as well as lab research for engineers and scientists.

 

Drone Application

Safety Inspections of machinery and infrastructure that contain pollutant and toxic gasses are simplified and put safety first when using MWIR cameras on drones.

MWIR by FLIR

Handheld Camera

GFX 320
The GFX320 visualizes hydrocarbon leaks and is certified [by whom?] for use in hazardous locations.

Mountable/Drone Camera
G300-A
Lightweight drone mountable camera, visualizes gasses for monitoring installations in remote or hazardous areas.

 

Long Wavelength Infrared (LWIR)

Long WaveLength Infrared cameras are the primary devices used in temperature inspection practices. The LWIR camera can detect distinct temperature differences important in the home inspection field for visualizing poor insulation, water damage, and damaged electronics.

LWIR is typically defined as the 8.0 – 14.0 μm wavelength range.

Long Wavelength Infrared is the most commonly used form of Infrared technology. LWIR imagers detect radiated temperatures that indicate important information to the operator. For more information on LWIR cameras and there applcations please check out our GETTING STARTED WITH THERMAL IMAGING post.

LWIR cameras on drones can be applied in a variety of ways

Drone Application

  • Solar Field Scans
  • Home Inspection
  • Farm and produce analysis

 

LWIR by FLIR

Mounted Camera:

FLIR’s PathfindIR II
The PathfindIR is a Long Wave Infrared imager intended to be attached to vehicles for night use. This LWIR detects road hazards in complete darkness highlighting road hazards such as vehicles, animals, and people. The PathfindIR makes night driving safer and detects hazards from four times farther away than headlights do.

 

Drone Cameras:

Zenmuse XT2
4k Camera + Thermal Sensor. Uses MSX technology to take high quality infrared imagery.
Note: This camera is a weather resistant camera which can be used in the rain, snow, smoke, and fog. Using a weather resistant drone such as the DJI Matrice 200 Drone.

 

Handheld Camera:

T1020 HD
Implements HD Resolution, MSX, and UltraMax. With the ability to detect temperature differences down to <20 MK. While capturing up to 3.1 Million pixels per image.

 

What SWIR, MWIR, and LWIR Are Not

Many thermal photographers often confuse these technologies with night vision, so it’s important to clarify the distinctions.  Night vision devices are cameras that enhance small amounts of visible light to illuminate an area.

Besides MSX implementation infrared imagers do not capture visible light.

 

Next Steps

Choosing between which type of Infrared Device is challenging! Knowing the Difference between the each wavelength and how they operate is the first step. You might also be interested in some of our other recent posts regarding thermal imagery: GETTING STARTED WITH THERMAL IMAGING and MSX implementation

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About the Author

Ethan Swansey