- Show them the relevant eye safety graph from
Ronja Metropolis/Tetrapolis legal issues section or
Ronja Inferno legal issues section.
- The eye safety has been determined by calculation, which is performed
by the Gnuplot program. The formulae used for the calculation are in the
Gnuplot source. You can find the source at the same link.
- The source is commented so the inspection should be able to check that
the calculation is done physically correctly and in accordance to the
- The calculation is based on worst case power output of the LED from
datasheet and lens gains measured on real lens samples using Ronja Benchpress.
- Worst case is being taken into an account, where the device is not focused
into the receiver far away, but instead misfocused into the observer's eye.
For this calculation, shift of 40mm is taken into account. 20mm is distance
between middle of the focus path (nominal position) to the front end
of the focus path. Another 20mm is allowance for manufacturing errors.
- For Ronja Inferno, the limits are exceeded when looking with binoculars
from less than 20 meters. This is prevented by the warning label put on the
- For Ronja Interpolis and Tetrapolis, the maximum allowed exposure
time drops down to 300ms for stronger binoculars in particular very close distance.
However, observing Ronja with binoculars from so close is
unpleasant, because the LED image appears as a large very bright red light. The user will
instinctively blink and turn away. The nominal blink reflex duration is 250ms.
Therefore the observer is protected even in this case.
In Switzerland it seems there is no law that would limit
non-laser visible and infrared sources from the eye safety point of view. See also
Ronja Metropolis/Tetrapolis legal issues and
Ronja Inferno legal issues.