STEMMER IMAGING

The SWIR wavelength band extends from 1050nm to 2500 nm and the standard wavelengths available in these lighting ranges are 1050 nm, 1200 nm, 1300 nm, 1450 nm, and 1550 nm. Special wavelengths are available on request. A camera with a dedicated SWIR camera is needed when using SWIR wavelength light.

Although SWIR radiation is not visible to the human eye, it interacts with objects in a similar manner as visible wavelengths. Images from an SWIR sensor are therefore comparable to visible light images in resolution and detail although they are only displayed in monochrome.

SWIR cameras are available for a wide variety of applications and industries. Since silicon is transparent to these wavelengths SWIR cameras are useful in semiconductor applications where they can ‘look through’ silicon layers. Water, however, strongly absorbs infrared light in this region, making it appear opaque in the image.

The Prox Light series of spotlights feature single 5W LEDs housed in small 30mm barrel sensor housings. The housings are the industry standard threaded barrel M30x1.5 style used for proximity and photoelectric sensors. Like the entire line of Smart Vision Lights, the Prox Light series includes an integrated constant current driver inside every light along with built-in strobe input with option for PNP or NPN trigger control. The integrated driver eliminates the need for wiring between the light and external driver and limits current to the LED while providing constant stable power. The light’s PNP or NPN strobe triggers control light pulse timing.

The Brick Light® has 6 high output, high current LED's in a small housing. Brick Light® also includes an integrated constant current driver with a built in strobe input with option for PNP or NPN trigger control. The integrated driver also includes variable light intensity control. Light can be controlled by a manual potentiometer or a 0-10VDC analogue signal.

SWIR applications

The strong IR absorption by water in SWIR imaging allows easy checking of fill levels of water-based liquids in bottling applications. Another interesting application area is that of identifying water distribution in plants in order to improve crop yields. The transparency of silicon to SWIR radiation facilitates semiconductor and solar cell inspection. Impurities in semiconductor crystal ingots and cracks in polycrystalline material can be detected. 3D wafer inspection or dicing, microscope inspection of structures or wafer alignment and BGA soldering checks through silicon are other typical applications.

High temperature imaging (between 250 °C and 800 °C) makes SWIR very useful in the inspection of hot glass materials early in fabrication. This includes control of temperature uniformity during forming and cooling and the detection of defects such as cracks, breakage, tamper, contaminants and chips.

Other applications include:

• Finding hidden moisture in packaging
• Inspecting tamper proof security codes
• Locating damaged or bruised fruit
• Verification of coating or dryness uniformity in bulk materials
• Anti-counterfeiting inspection
• Surveillance
• Inspecting objects masked by smoke, steam or fog

To help determine the most suitable SWIR wavelength for an application, a Smart Box For Testing SWIR Wavelengths is available which contains LEDs with wavelengths of: 940 nm, 1050 nm, 1200 nm, 1300 nm, 1450 nm, and 1550 nm.