What is SWIR Imaging?

Shortwave infrared (SWIR) imaging detects light in the 900 nm to 2500 nm wavelength range, which is invisible to the human eye. Unlike thermal imaging (MWIR/LWIR) that sees emitted heat, SWIR imaging captures reflected light. This fundamental difference means images taken with SWIR cameras have shadows, contrast, and spatial details much like a standard B&W photograph. Moreover, a key advantage of SWIR light is its ability to penetrate atmospheric obscurants like fog, smoke, and haze better than visible light.

The Technology Behind SWIR Cameras

Standard silicon sensors, found in smartphone cameras, cannot detect light beyond about 1000 nm. However, SWIR cameras rely on specialized sensors mostly made of indium gallium arsenide (InGaAs). InGaAs has a suitable bandgap energy ($0.73$ eV) allowing to efficiently absorb and convert SWIR photons into an electrical signal.

Compared to long wave thermal imaging (LWIR), the shorter wavelengths of SWIR light allow high resolution imaging, capturing much finer details with the same size optics.

Advancements in SWIR Sensors

Modern SWIR technology has expanded the following sensor capabilities:

• Broader VIS-SWIR Spectrum: Some sensors, like Sony’s SenSWIR™, can detect a wide spectrum from visible light to SWIR (400 nm to 1700 nm) on a single chip. This is useful for applications such as multispectral  imaging, laser beam profiling or photonics on chip inspection. 
• Extended Wavelength Range: By modifying the InGaAs alloy, “extended-range” sensors can detect up to 2200 nm. This is especially useful for hyperspectral imaging to identify materials based on their unique molecular absorption properties (ex: water or hydrocarbons).
• Noise Trade-offs: As electronic noise increases at longer wavelengths,  integrated cooling systems are often required to maintain image quality. 

Axiom Optics SWIR Cameras and Solutions

Axiom Optics supplies high-performance InGaAs SWIR cameras for scientific and industrial applications. Our cameras feature:

• High frame rates for capturing fast events: the C-RED cameras are our fastest InGaAs cameras with 600 fps in full VGA resolution and >1,000 fps by windowing the sensor. C-RED cameras are ideal for applications such as free-space optics (FSO), adaptive optics, target tracking, spectroscopy, welding or additive manufacturing.
• High resolution for maximum detail: we offer several SWIR cameras equipped with the latest Sony IMX992 sensor with 5.3 MP and the smallest pixel pitch on the market (3.45 µm). These cameras are ideal for semiconductor and solar cell inspection (with a SWIR microscope setup for instance), laser detection, tracking and space applications. 
• High sensitivity with very low noise for low-light conditions. The C-RED 2 camera comes with a readout noise of only <30 e- and a low dark current of ~300 e-/pix/sec. It allows long exposure times for the most photon starved applications such as electroluminescence (EL) and photoluminescence (PL) inspection in semiconductors.
• Compact and lightweight designs for drones and portable systems. The Alvium SWIR cameras with up to 5.3MP are the lowest SWaP cameras we offer. They are available with housing or as bare-board level cameras.