Use Case Tutorial:

Detecting Hidden Scratches in Transparent Materials Using DoLP Range Sliders.

With ArenaView DoLP polarization display tutorial

Polarization can be used to detect internal stress and scratches in transparent materials such as plastics or glass. In this example we look at how using LUCID’s polarization camera along with LUCID’s Arena Software Development Kit can measure the Degree of Linear Polarization (DoLP). By enabling the ArenaView GUI to display the DoLP images, stress and defects can be detected in transparent materials which would otherwise go unnoticed with regular visible light cameras.


  • Triton (TRI050S-P) or Phoenix (PHX050S-P) 5.0 MP Mono Polarization Camera (Color support coming soon)
  • Triton 5.0 MP Polarized Firmware Version: or higher or
  • Phoenix 5.0 MP Polarized Firmware Version: or higher
  • Arena SDK – Win 32/64-bit Version: or higher

The Transmission Technique

For inspecting transparent materials, the transmission technique of using a polarized light source to shine light through a transparent object with a polarized camera on the other end is effective in detecting internal stress, internal debris, and surface scratches. The angle and degree of the polarized light source will be altered as it passes through the object. Any changes in the DoLP will be displayed in Arena SDK. ArenaView has a built in DoLP display that when enabled, maps a color scheme to represent polarization information.


Degree of Linear Polarization (DoLP)

Image 1: Monochrome image of plastic cell phone case

Phone Case Plastic Scratches

DoLP Grayscale levelsWhen inspecting for defects on a clear material such as a protective shell of a cellphone made of clear plastic, certain defects may be hard to identify with standard monochrome cameras. When imaged using a polarization camera, these defects can be identified and enhanced using the DoLP information from the image.

What is Degree of Linear Polarization (DoLP) ?

DoLP is a measured value that represents how much of the light is actually polarized to a specific angle. The scale of DoLP ranges from 0 to 1. Perfectly linear polarized light will have a DoLP of 1 whereas unpolarized light, such as sunlight, would have a DoLP of 0. Like AoLP, a color scheme with saturation levels can be mapped to DoLP values.

Enabling DoLP Display in ArenaView GUI

Step 1. Set camera pixel format to DoLP Mono8.

Set the camera pixel format to “PolarizedDoLP_Mono8” to enable on-camera processing and output of DoLP information.

Important note: Some of the features in ArenaView like “PixelFormat” are disabled if the stream is already enabled. Close the stream first and then check if you are able to change the settings.

Step 1b. Switch to Options Tab

After “PolarizedDoLP_Mono8 is selected and the stream is started, open the Options Tab located below the window
options bottom tab

Polarized DoLP Pixel Format

Step 2. Enable “Range Selector” display format.

A plastic cellphone case is placed on top of a polarized back light. In the DoLP view, defects such as scratches become more prominent. However, smaller defects are still difficult to distinguish from small particles and dust. This can be addressed by changing the color representation of the data and improving the contrast. Select “Range Selector” display format in the Options panel to adjust the degree range and outside color.

Invisible scratches being detected by polarized camera

Step 3. Reduce degree range slider and set outside range color.

To enhance the contrast more, the DoLP range slider can be adjusted to change the minimum and maximum DoLP, helping to enhance smaller and finer scratches in the image. Experiment with the slider to find the best possible image contrast.

Adjusting Polarizaed DoLP range slider on transparent cell phone cover


The DoLP view can not only display defects that are otherwise hard to see with standard cameras, it can also enhance the contrast of smaller defects and improve defect identification rate.

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