What is a SWIR camera?

A SWIR camera images short-wave infrared light, the band just beyond what silicon image sensors can detect. Most use an indium gallium arsenide (InGaAs) sensor. Like a visible camera, it forms its picture from reflected light, so the images look like black and white photographs, but materials such as water, plastics, silicon and some inks look very different from how they appear to the eye.

What wavelength range does SWIR cover?

Definitions vary, but SWIR is usually taken as roughly 900 to 1,700 nm for a standard InGaAs camera, which is set by the cutoff of the InGaAs material itself. Extended SWIR cameras push the long end out to about 2.2 or 2.5 µm. Some InGaAs sensors are also built to respond down into the visible range, so one camera covers visible and SWIR light.

How is a SWIR camera different from a thermal camera?

A thermal camera (long-wave infrared, about 8 to 14 µm) sees heat given off by objects, so it works in total darkness and shows temperature differences. A SWIR camera sees reflected light, so it needs light from the sun, the night sky, halogen lamps or SWIR LEDs, and it shows surface detail and material differences rather than temperature. SWIR light also passes through ordinary glass windows, which block long-wave thermal imaging. Only very hot objects, such as molten glass or metal, give off enough of their own light to show up in SWIR.

Why can't a normal camera see SWIR light?

Standard CMOS and CCD sensors are made of silicon, which becomes transparent to light beyond about 1,100 nm and loses most of its sensitivity well before that. Light in the SWIR band passes straight through a silicon sensor without being detected. SWIR cameras use materials that absorb at those wavelengths, most often InGaAs, or newer options such as quantum dot films and germanium on silicon.

Why does water look dark in a SWIR image?

Water absorbs strongly in bands near 1,450 nm and 1,940 nm, with weaker bands at shorter wavelengths. Anything containing water, such as wet patches, bruised fruit, moist grain or a liquid inside a container, absorbs more light in those bands and appears darker. This is why SWIR cameras are used for moisture checks, fill-level inspection and food sorting.

What can a SWIR camera see through?

Depending on the material and thickness, SWIR light passes through silicon, many plastics, some paints, coatings and dyes, ordinary glass, and haze or light smoke better than visible light does. That allows inspection through silicon wafers, fill levels through opaque plastic bottles, and clearer long-range views in hazy air. It does not see through metal, thick fog or walls, and results always need to be tested on the actual material.

Do SWIR cameras need special lenses?

Usually, yes. Lenses designed for visible light can lose transmission and focus differently in the SWIR because their coatings and color correction are optimized for shorter wavelengths. SWIR-corrected lenses use coatings and glass designs suited to the band the camera covers, and they should match the sensor size and pixel pitch. Standard mounts such as C-mount are common.

What lighting works with SWIR cameras?

Light sources that emit in the SWIR band. Sunlight and halogen or other incandescent lamps contain a lot of SWIR light. SWIR LEDs are made at specific wavelengths, commonly around 1,050, 1,200, 1,300, 1,450 and 1,550 nm, and are used when a particular material contrast is needed. White LEDs and fluorescent lights emit very little SWIR light, so they are a poor choice for SWIR imaging.

Does a SWIR camera need cooling?

It depends on the exposure time and the noise you can accept. Dark current in InGaAs rises steeply with temperature, so short exposures on a bright inspection line often work with uncooled or temperature-stabilized cameras, while long exposures in spectroscopy, astronomy or NIR-II fluorescence imaging usually call for thermoelectric cooling or deep-cooled scientific cameras. Extended SWIR sensors typically need more cooling than standard InGaAs.

What is extended SWIR?

Extended SWIR (eSWIR) cameras respond beyond the roughly 1,700 nm limit of standard InGaAs, out to about 2.2 or 2.5 µm. They use InGaAs with a different composition or other materials such as mercury cadmium telluride. The extra range reaches more absorption features of plastics, minerals and chemicals, at the cost of higher dark current and usually more cooling.

Are SWIR cameras subject to export controls?

Some are. Depending on their specifications and design, certain SWIR cameras, sensors and camera cores are controlled under export regulations, for example the US Export Administration Regulations, and products designed for military use can fall under ITAR. Many other SWIR cameras are not controlled. Ask the supplier for the export classification of the exact model and allow time for any licence if it will cross borders.

What should I send to get a quote?

Describe the application, the material or scene you need to see, the wavelength range, the resolution and frame rate, whether it is an area-scan or line-scan job, the interface your system uses, the quantity and your timeline. If you have sample images or know the working distance and field of view, include those too. That is enough for a supplier to suggest a camera, lens and lighting and come back with a quote.

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Last updated 26 October 2026

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SWIR light sources and lasers are invisible to the eye and can cause eye and skin injury at sufficient power, whatever their wavelength. Halogen illuminators run hot, and inspection equipment on production lines involves moving machinery and electrical work. Follow the manufacturer's instructions, laser and lamp safety requirements, electrical and lockout procedures, and applicable occupational safety regulations. Nothing on this site replaces them.

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