Visible polarization

The Baumer polarization CX series cameras integrate on-chip polarizing filters at the pixel level. This way, they feature higher contrasts in intensity images for inspections on low-contrast or reflecting surfaces and transparent materials. Besides light properties such as wavelength (color) and amplitude (brightness), this efficient approach also evaluates  the light wave’s direction of oscillation or polarization caused by effects of reflections and refractions on materials.

Your benefits:

• Higher contrasts in the intensity images of low-contrast material surfaces which polarize light to different degrees locally, e.g. carbon-fiber-reinforced polymer CFRP
• Higher contrasts in the intensity images of reflecting surfaces by suppression of the reflected light portions, e.g. glass, plastic and metallic glossy materials, such as packaging films
• Visualization of residual stress by refracted light on transparent materials, e.g. glass or plastic

Examples:

Left: Imaging of monochrome camera
Right: Imaging of polarization camera with colored degree of polarization

When describing light as an electromagnetic wave, each individual oscillations plane can also be referred as a polarization plane. For the use of imaging polarization applications, the following polarization types have to be distinguished:

• Unpolarized light consists of many superimposed light waves such as sunlight, light emitted by electric bulbs and most types of LEDs.
• Linearly polarized light consists of only one oscillations plane. It’s present in many applications and can be easily evaluated by polarization cameras.
• Elliptic and circular polarized light, which can occur during the inspection of glass, for example, depending on the light waves’ amplitude and phase constellation and which must be considered in system design.

Beyond polarization by reflected and refracted light, illumination allows linear polarization by polarizing filters. For example, these are required in inspections on reflecting metal surfaces.
During image acquisition, the polarizing filter is suppressing the content of linearly polarized light in order to avoid reflections and overexposure in some sections of the image.

Packaging of blister packs

Visualizing residual stress

Inspections on product packaging

Inspection on deformations