The POL camera is a black and white camera and offers beside the raw image four selectable directions of polarization: 0°, 45°, 90°, 135° to acquire a multi-channel image. The raw image shows all directions of polarization. In color mode the images are displayed in false-color.
After image acquisition, the selected directions of polarization are extracted from the raw image and provided as multi-channel image.
The default value for multi-channel images shall be Single Channel. This is valid for all TCA job templates.
If single channel is not activated, the merged image is displayed. The merged image is an additive image of all selected channels and therefore much brighter than the single channel images.
- Axiocam 705 pol is installed.
- In the Extended Camera tool > Mode section, the camera mode B/W is selected.
- In the Extended Camera tool > Mode section, Live speed high is selected.
- In the Extended Camera tool > Model Specific section, the channels 90° and 135° are selected.
- On the Display tab, Single Channel is activated. It is not possible to display more than one channel at the same time. You can switch between the two image channels to differentiate immediately between metallic and non-metallic particles. The Pol-90° channel and one additional channel, i.e. 0°, 45° 135° is mandatory for correct differentiation of the particle types metallic-shiny and non-shiny.
- To display metallic particles bright shining, in the Image View, on the Display tab, select Pol-135 channel. Note: Depending on the particle surface and its orientation on the filter membrane, it might be that only smaller areas of the metallic particle appear bright shining. This is a general effect using polarization and is independent of the applied technology.
Note: Also, the 0° or the 45° channel can be selected to display metallic particles bright shining, but it is recommended to use the 135° channel. In this setting, metallic particles are not outshined which leads to a better image quality in the report. Furthermore, foamed filter membranes show less reflections. - In the image, the metallic particle is displayed in Pol-135 channel.
- To display metallic particles dark black, in the Image View, on the Display tab, select Pol-90.
- In the image, the metallic particle is displayed in Pol-90 channel.
Example: Non-metallic particle
Non-metallic particles do not react on polarization with a change in brightness from silver white to dark black. In most of the cases you can observe a change from gray to darker gray, even for those materials with reflecting brighter areas. They never get dark black when using crossed polarization.