LIGHT - ANGLE
Light beam creates a donut shape, lighting the fibres perfectly and minimising light entering the pupil.
LIGHT - COLOUR
The different colours in the iris are highly important. Thus perfectly white coloured lighting is crucial. If the lights were even slightly yellow or blue, then a dark orange pigment in the iris could seem brown or a white fibre could seem yellow.
After testing hundreds of different LEDs, we sourced highly specialised "certified White" LED. Their operating colour range is very narrow. To increase the accuracy of their colour, the electronic controler is programmed to calibrated the voltage, so colour will not change even if battery voltage is too high or too low (see battery managment for details).
The lights are also Pulse Modulated. Without going into too much detail, the LEDs are always at 100% intensity, but can be dimmed by Pulsing the light. Its invisible to you or the camera, but the light waves remain the same length (same colour), but arrive pulsed at very high frequency. This allows for hight quality photography lighting, but reduced discomfort to client.
LIGHT - NOISE
The iris is a shiny sphere. Photographing it, is like trying to photograph the surface of a mirror ball. All the surrounding lights will be reflected in the photo and instead of being able to see the surface, one would see all the light reflections. If you've tried to photograph a eye with a regular camera, you will know that this is a problem.
To eliminate nearly all internal and external light noise, the IEv2 is designed:
to come in contact with your clients face (eyebrow, side of nose & cheek)
with a case made of none reflective black plastic
with 3mm diameter LEDs with a special shaded/blinkered design which cuts all side light, like a spot-light
The only reflections are the 2 small white dots from the LEDs.
Question : Why not design the IE to have those reflexions in the pupil area of the photo?
During our prototype testing phases, we realised that we preferred to have the perfect lighting angle of the fibres as it was very easy to rotate the iriscope a little and take another shot. In practice it turns out that those reflections are very small and its very rare that one would miss key information in those 2 tiny areas, often if there is a detail in that area it is visible around or next to the reflection and one can quickly take another photo of the iris.