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Dual-band SWIR line scan camera reveals ‘hidden’ vision data

3 Apr 2017

The new Wave series of dual-band line scan cameras from JAI operate in the Short Wave InfraRed (SWIR) region of the spectrum. The WA-1000D-CL simultaneously acquires and precisely aligns images from SWIR light between 900 and 1400 nm on one sensor and from 1400 nm to 1700 nm on the second sensor, even when objects are moving at high speeds. This has the potential to enhance current machine vision systems by revealing information that can’t be seen when using just the visible and/or the near infrared light spectrum.

The key benefit of splitting the SWIR light across two different wavebands and sensors is that it makes it possible to utilise the fact that SWIR light absorption levels in different chemical components varies according to the wavelength of the SWIR light. The differences in light absorption levels produce light and darkness differences for specific objects in the two images, which can be used as an inspection criterion.

Typical automated optical inspection applications for the WA-1000D-CL include:

  • Food inspection looking for unwanted moisture (in tea, biscuits, grain etc.)
  • Quality checks in pharmaceutical manufacturing
  • Determination of dryness level in various industrial dying and coating processes
  • Waste sorting isolating different kind of plastics.

The specific bandwidth split used in the WA-1000D-CL is particularly useful for the detection of water moisture levels. In applications such as pharmaceutical inspection, waste sorting or other industrial processes, it may be necessary to choose a different split of wavelengths in order to give the desired imaging results needed to solve the specific inspection challenge.

The camera uses a prism and a combination of bandpass filters to divide the incoming light into the 900 – 1400 nm and 1400 – 1700 nm wavelength bands and direct it to two separate indium gallium arsenide image sensors. These special sensors are responsive to wavelengths over 900 nm where traditional CCD/CMOS silicon sensors are unable detect light.

Images are output as 2 x 8-bit, 2 x 10-bit or 2 x 12-bit in two video channels (ch1/ch2) via the Camera Link interface which is available with dual-base configuration or 2-tap medium configuration. The WA-1000D-CL has a resolution of 2 x 1024 pixels and a maximum line frequency of 39 kHz (39,230 lines/second). A variety of pre-process functions include pixel gain correction, flat-field correction, LUT and gamma correction.

These SWIR cameras do not require cooling and can make use of off-the-shelf optics, unlike MWIR cameras that require custom lenses and windows made of expensive materials. The M52 mount meets the recommended machine vision lens guidelines for large sensor mounts. Cost of ownership of the Wave series is comparable to a standard machine vision camera.

JAI Wave

Prism-based dual-band SWIR line scan camera detecting wavelengths from 900 nm to 1700 nm at 1k line resolution with 39 kHz.