A deep dive into polarisation

The electric field oscillates due to its interaction with the magnetic field and vice versa. The two waves have the same wavelength and are typically in phase with each other. It’s the combination of these two disturbances that forms the electromagnetic wave.
The light spectrum sits within a larger electromagnetic spectrum which ranges from gamma rays through to radio waves.
(The UV, visible and IR spectrums make up a small fraction of the various wavelengths that exist)
So how does polarisation work with these?
The polarisation of a wave indicates the direction of the electric field’s amplitude. Polarised light means that all waves would have the same polarisation.
Edwin Land, born in 1909 in Connecticut, invented Polaroid, the world's first polarising material for commercial use, in 1929. He founded the Polaroid Corporation in 1937 in Cambridge, Massachusetts. The company initially produced Polaroid Day Glasses, the first sunglasses with a polarising filter.
Source: https://en.wikipedia.org/wiki/Polaroid_Eyewear


Where would this be useful?
The ideal illumination solution for objects that are shiny and curved would involve high end illumination sources including ...
Circular and elliptical polarisation
These are a little bit more complicated. If the phase of the electric and magnetic fields is not the same, then the wave is said to be elliptically polarised. When the two are added, it traces an ellipse around the axis.

Is there quantitative a way to specify the polarisation of light?
Yes, by using the Stokes vector, four numbers that define the direction and magnitude of an electromagnetic waves polarisation - whether its unpolarised, partially polarised, or fully polarised.
Polarisation by reflection
Application examples
Detection of mechanical stress in filter can lids
Film inspection of card decks
Film inspection of card deck tear tabs
Inspection of shiny and reflecting surfaces
Advantages of Polarisation
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 and de that simply could not be seen using any other imaging technique.
Please talk to us if this technology may be of interest to you.
Please talk to us if this technology may be of interest to you.
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