Physics/Science of Light (PART 9)

Physics/Science of Light

(How you could implement it + create dramatic compelling art scenes)

REFRACTION AND CAUSTICS

Refraction works on the same principles as the Fresnel equation; the level of reflectivity is contingent on the angle at which light hits the surface.

On a glass surface, an interaction occurs as the light passes through it; the level of refraction is also dependent on the angle the light hits the surface.

If you have a circular surface (such as a lens surface), you can actually reverse the image your viewing so that anything behind the ball get refracted and reversed (upside down). This happens because of the way the light is bouncing through.

Why does it happen?

The light slows down. The light passes through dense surfaces more slowly. Whereas if it travels through a less dense surface it will pass through it quickly. Light travels very quickly through air and water; which causes a refracted reflection to form. The more extreme the angle the light is striking water, the higher the level of bending/refraction will appear on the water's surface. You can get some crazy effects with refracted reflections when light hits water at a more dramatic angle.

Refraction and Caustics are caused by the same thing: materials that slow down light.

CAUSTICS

When a light source passes through a transparent object that has a surface prone to refracting, you can expect to see a focal point of light being cast in the shadow as a result of this.

You can see this type of phenomenon here where the light is passing through the transparent glass object. If the density of the medium inside the transparent object is thick this will cause the light cast onto the shadows to bend more dramatically.

Studying and learning how refraction and caustic effects works is important if you want to paint glass or transparent objects.

COLOUR SHIFTS

So there are a couple of processes which cause colour shifts in transparent medium; one of them is called "chromatic aberration".

For instance, when you have a white light coming in a lens, this light will split and separate into different colours. (You can see the separation of the white light as it passes through the lens and splits into red and blue colours).

It doesn't produce a huge effect but it is slightly visible if you observe. This effect can take place on energy efficient windows, or through water.

As the angle of light increases the split between the red and the blue (or any other colours from the spectrum) is also going to increase.