Laptop/Notebook Polarizars

Polarization

The Wave’s Electric field is the direction that is described by the polarization of light. Polarization is an ability of waves that defines the orientation of their oscillations. When light travels in space, in most cases it propagates as a transverse wave, the polarization is upright to the wave's direction of travel. The electric field may be oriented in a single direction, or it may rotate as the wave travels. In the latter cases, the oscillations can rotate rightward or leftward in the direction of travel, and which of those two rotations is present in a wave. Without the polarizer, the screen would only show a white display. This is caused by the scattered light not being filtered into one uniform path.
When a Laptops  LCD screen is scratched, it’s not the glass that is damaged, it’s actually the polarizer. It’s a common misconception that an LCD screen’s outer surface is made of glass, that’s why so many people assume that when a screen is scratched, it’s the glass that is damaged.
This is also the reason that cleaning your screen properly is important. Many people believe that the outer layer of an LCD screen is glass and use glass cleaner to clean the screen. Harsh solvents like ammonia may damage the polarizer and cause a cloudy or distorted display.