Singapore 20th August 2010
Most people do not realize that we can’t see light, unless we look directly into a light source. We see reflections. Light that travels through air space is invisible, until it hits particles of dust or water. This is one of the main reasons that stage productions use smoke machines for instance so that the light beam suddenly becomes visible. A big search beam is only visible because of the dirt and pollution in the city air! Ever tried a light beam on a clear night out in the country side? Indeed zip…
One of the demonstrations we had in Philips’ lighting application center was a light beam of which the light source was hidden in a black ceiling and the floor area below the beam concealed so that any reflections from the floor could not be seen. Suddenly by moving a hand through the beam the light became visible reflecting of the hand.
Today I had some conceptual lighting discussions about using light to create unexpected scenes otherwise invisible. It is a “trick” used in stage productions but also in architectural lighting design. On stage the material is called a scrim, a sort of perforated material that act as a screen when you project light onto it but act as a see-through panel if you project light in the space behind it. Because the brightness in the first case is higher in front then behind the screen your eyes are focused on the highest brightness which is the front of the panel. The contrast with the darkness behind assures you can t see beyond it. But by creating a higher brightness behind the screen the world behind that screen suddenly becomes visible. We decided to apply that principle to create some unexpected (lighting) scenes in a corporate entertainment lounge.
This brightness contrast ratio is also key in many situations involving glass windows. Ever wondered why it is sometimes so difficult to look out of a window to enjoy the exteriors views at night? It is simply because inside is brighter then outside and as a result the window reacts as mirror! That is also one of the reasons that shop windows are often really bright inside, so they can compete with sunlight or bright exteriors. If not you would not be able to enjoy the displays but only the reflection of yourself.. 🙂