December 6, 2012

Light Refraction in Glazing

Written by Rebecca Clayton

"When light travels through glazing the light waves slow"

For the purposes of understanding light refraction it is important to note that all light travels as waves. For your eyes to pick up images what we actually see are reflected waves of light from the object we are viewing.

When light waves travel through a transparent surface such as glass there are some elements of reflection but the majority of the light travels through the glass and to our eyes. When light travels through glazing the light waves slow causing light refraction.

To explain this it is easier to imagine a car travelling down a road. If the wheels on the right suddenly hit quick sand that side of the car would try to slow down, this would pull the car around to the right. It's the same for light; the top of the ray of light hits the glass boundary first and slows down. This has the effect of pulling the ray of light around in a new direction.

"The more optically dense the material the more the light slows"

The more optically dense the material (generally the thicker it is), the more the light slows so the larger the refraction and the smaller the ‘angle of refraction’.

When the light waves emerge from the glazing element the waves can speed up again. This is what we see as refraction. The most visible and easily spotted instance of light refraction and the effect it can have on our view of images is seen in a glass of water with a straw. The equations that describe this phenomenon are called Frensel Equations.

"This can sometimes result in image distortion in glass assemblies"

When you introduce this behaviour into a double glazed unit you will get what is known as ‘double refraction’ as the light waves have to travel through two or multiple glass masses which may result in a distorted image. You may also get a level of reflection within the glass cavity where the initial glass refracts through the glass surface, when it hits the second pane of glass, will reflect slightly, bounce back of the initial pane and then refract through the system.

This can sometimes result in image distortion in glass assemblies. Distortion always seems more apparent in the units with the most light as the image also reflects from the face of the glasses inside the unit.

If you have any doubt about an IQ Glass panel and whether it is being effected by light refraction please do contact your IQ Glass Contract Manager who will happy to talk through this with you.

IQ Glass: hello@iqglassuk.com, 01494 722880