Why light reflected off of my calculator screen turns bluish?

So, I was in class listening to my lecturer when I notice something intriguing. I was looking at the reflection of a lamp on the screen of my calculator. I paid close attention to the colour of the light reflected of my calculator and realised that when I rotate my calculator by about 90 deg, the colour of the lamp reflected off of it changes colour gradually from blue to purple. The colour that I see with my eyes and through the pics I took here is almost the same.

As you can see the colour of the light reflected off is bluish here
IMG20190920090649.jpg


But here when rotated clockwise at about 90 deg, the colour of the light reflected looks purplish
IMG20190920090659.jpg


I'm just wondering whether or not this has something to do with the polarization of the light wave. Anybody has any explanation as to why light behave this way given this circumstance?
 
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The effect is called dichroism.
 

sophiecentaur

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The effect is called dichroism.
Dichroism is a term to describe the effect when light of different wavelengths passes through layers of different transparent materials. There are always reflections at any interface and the multiple reflections at several layers - like air over a thin oil film, floating on water. The different wavelengths will have different phase shifts through the layers (same delay but different shifts) and that will cause different results of the interference- producing maxes and mins for different wavelengths in any given angle. The effect can be strong or mild. The LCD screen produces a mild colouration whereas the layers on a bird or insect's wing can produce stunning effects due to selectivity of different wavelengths. The colours can be a lot stronger and more noticeable than what you could ever get with a simple glass prism or a pigment.
The Polarising layers in an LCD produce the effect as an unwanted byproduct. The more you pay, the better they tend to be. Note how a bit of pressure on the glass (careful) can cause colour fringes.
 

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