Short-wave infrared (SWIR)

Definition and Spectral Range

Short-Wave Infrared (SWIR) cameras are infrared imaging systems that operate over a spectral range typically spanning ~1.0 µm to 1.7 µm, with some systems extending to 2.5–3.0 µm. There is no universally enforced wavelength boundary between NIR and SWIR; manufacturers may define the transition differently, and specifications often overlap. In practice, application requirements are far more important than nomenclature.

Imaging Characteristics

At ambient temperatures, SWIR cameras are generally not used for conventional thermal imaging. Instead, they detect reflected light and emitted radiation, making them highly effective for contrast-driven inspection tasks. InGaAs detector technology is commonly used, offering high sensitivity and low noise across the SWIR band.

Key Applications

Semiconductor and Wafer Inspection

One of the most established applications for SWIR cameras is semiconductor and wafer inspection. Operating typically between 1000 nm and 1400 nm, SWIR systems are used to detect voids, cracks, and trapped air layers in wafer-to-wafer bonding processes. With controlled illumination, SWIR cameras provide exceptional contrast for identifying internal defects that are invisible to visible cameras.

Laser Profiling and Alignment

SWIR cameras are also widely used for laser profiling and alignment, particularly for lasers operating near 1.06 µm. They enable visualization of beam shape, power distribution, and alignment accuracy. Optical filtering is frequently required to protect sensors from high laser intensities.

High-Temperature Industrial Measurement

In high-temperature industrial environments, radiometrically calibrated SWIR cameras enable non-contact temperature measurement from approximately 450 °C to 1800 °C. Applications include molten metal handling, casting, forging, and heat treatment. Unlike single-point pyrometers, SWIR cameras provide full-field thermal data, allowing operators to assess temperature uniformity and process stability in real time.

Metal Additive Manufacturing (3D Printing)

SWIR cameras are increasingly critical in metal additive manufacturing, where they are used to monitor melt pool temperature, thermal gradients, cooling rates, and laser stability. Compared to spot-based sensors, SWIR imaging delivers spatially resolved temperature data that supports improved process control, mechanical properties, and part quality. Specialized systems often incorporate laser-blocking filters tailored to the printing process.

Selection Considerations

Engineers evaluating SWIR cameras should consider: