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New polarisation line scan camera reveals unique properties of materials

23 Nov 2017

The new Teledyne DALSA Piranha4 Polarization line scan camera represents a breakthrough in machine vision by revealing non-visible properties of materials that cannot be detected with conventional imaging. With three independent polarisation detection channels, this innovative camera enables high-speed, real-time detection of birefringence, stress, surface roughness, film thickness, and other physical properties.

The Piranha4 Polarization camera is the latest addition to the versatile Piranha4 series of line scan cameras. It measures the intensity of light arriving at the camera at different angles of polarization after it has interacted with the object being inspected. Polarisation imaging is a powerful technique that offers numerous benefits. It is not just surface roughness, scratches, dents and surface coatings that can change the polarisation state of the light, but also other physical properties such as stress or birefringence. This means that the technique can reveal information that simply could not be seen using any other imaging technique. When combined with phase detection, polarisation imaging is much more sensitive than conventional imaging. The Piranha4 Polarization camera offers exceptional performance:

  • It is equipped with a 2k CMOS line scan sensor with up to 70 kHz line rate for high speed imaging and features a CameraLink full interface.
  • The sensor has 3 lines fitted with nanowire micropolariser filters making these lines sensitive to 0°(s), 90°(p), and 135° polarisation states respectively. A 4th, unfiltered channel allows direct imaging of light of any polarisation.
  • Images from each of the filtered channels could be colour coded for display purposes.
  • Multiple regions of interest (ROI) can be set up for calibration and data reduction to further increase imaging speed.
  • This camera solution is much faster compared to other polarisation filter technologies and principles.

The Piranha4 Polarization camera can be used in transmission or reflectance applications. For both configurations a polariser is placed in front of the light source to create z-linearly polarised light which is used to illuminate the object. The change in polarisation states of the light coming from the object can be independently detected by the 3 different polarisation channels of the camera.

The technique can be used in a host of markets and applications, including:

  • Industrial automation
  • Electronics manufacturing
  • Food inspection
  • PCB-AOI (automated optical inspection)
  • Biomedicine

The compact, robust, low cost single camera system avoids costly and complex alternative hardware solutions since it is based on established machine vision technologies.