Friday, 19 June 2009

Invisible White Light!

Further to my last post, I've just discovered Ultra Magenta! It's not really ultra magenta of course - that's just my name for it. I experimented further with my digital camera and discovered that it could also see ultraviolet, which the blue and red sensors render as a kind of visible magenta!

Add my ultra magenta to my infra green (see previous post) and you've got invisible white light!

Think about it - a flash unit with an infra red and an ultraviolet source, both invisible to the human eye but the camera sees it as white light! The ultimate unobtrusive flash.

No - this is too good. It's probably been done...

I need to do tests, tests, yes, tests (mutter mutter...)


  1. Dr. Alcock replies……

    Dear ‘Confused’ of Ledbury,

    White Light may refer to:

    White Light/White Heat (1967), The Velvet Underground's second album.
    White Light (Gene Clark album), a 1971 album
    White Light (novel) a 1980 novel by Rudy Rucker
    "White Light" (The 4400 episode), a television episode
    "White Light / Violet Sauce", a single by Namie Amuro
    "White Light", a track on Demon Days, the second album by virtual band Gorillaz
    White Light (2001 film), a 2001 film
    White Light (2008 film), a 2008 Dutch film
    White is a colour, the perception which is evoked by light that stimulates all three types of colour sensitive cone cells in the human eye in nearly equal amount and with high brightness compared to the surroundings. A white visual stimulation will be void of hue and grayness.

    White light can be generated in many ways. The Sun is such a source, electric incandescence is another. Modern light sources are fluorescent lamps and light-emitting diodes. An object that does not alter the colour of light reflected from its surface will appear white, unless it has very high specular reflection.[??]

    Since white objects such as clouds, snow and flowers appear often in nature, human culture has many references to white, often related to purity and cleanness. The high contrast between white and black is often used to represent opposites. In some cultures like the Chinese, white is considered to be the colour representing death. On the other hand in many cultures white represents purity, freedom, and hygienic purity.

    The best known way to generate white light is by the process called incandescence, by a black body at various relatively-high temperatures. For example, the colour of a black body at a temperature of 2848 kelvins matches that produced by domestic incandescent light bulbs. It is said that "the colour temperature of such a light bulb is 2848 K". The white light used in theatre illumination has a colour temperature of about 3200 K. Daylight can vary from a cool red up to a bluish 25,000 K.

    Not all black body radiation can be considered white light: the background radiation of the universe, to name an extreme example, is only a few kelvins and is quite invisible.

    Perhaps you have stumbled upon a black body during the night and have suddenly realised that this is something totally new to your psyche and thus experienced a special eureka moment of “I’ve just discovered invisible white light!”

    Please do not be alarmed. Just lie down in a darkened room with no external stimulation for an hour or so until such time that you can feel able to return to the Pub for a reviving Pint. It is only a passing whim.