barbara jansen - BADA

mixing effect (Neumann 2012, Göbel, 2012, LBM, 2011).
So far, several experiments have been conducted to enhance the quality of
the colour mixing process. Different diffusor materials have been placed between
the RGB-LEDs and the optical fibre ends. Prototype adapters have been
built to increase the space between the LEDs and the fibre ends, enhancing
the mixing of the light by bouncing it through an extended cylinder (adapter)
between the LED and the fibre end. A combination of both techniques has
also been explored
The engineering department at the company GTE Industrieelektronik
GmbH, under the leadship of Christian Specker accompanied by two physicists,
has explored different solutions. One solution was to install a diffusor at
the focal point of the silicon lens of the LED in order to enhance mixing of the
coloured lights and also to collect the light afterwards via a converging lens
to increase the luminous efficacy. Two major disadvantages was discovered
with this method. Firstly, the added diffusor materials (increased interference)
absorb too much of the needed light energy. The second disadvantage
concerns the quality of the silicon lens, which is not manufactured in a high
quality process. All commercial LED components have a high mechanical tolerance,
which makes it impossible to add other precise optical equipment to
them afterwards. Currently, Specker’s team has reached the conclusion that
although this solution functions in a lab environment, i.e. in theory, it does
not withstand technical issues relating to the conditions under which massproduction
is carried out.
A second idea is to adapt a single optical fibre to a single LED chip of acceptable
quality which would be possible to manufacture commercially. If
this idea were to be realized, one would be able to buy three single LED chips,
red, green and blue. After connecting each of the three fibres to one of the
three LED chips, the fibres would then be connected to a single fibre. When
the three monochromatic light beams pass this gate, we would have three
different colours of light mix in a single fibre. This would have to be done for
each optical fibre in the textile (3-to-1). This technique is known and used
mostly for laser equipment used in research and development. It has not yet
been subject to mass-production with many fibres, partly because it would be
too costly. Specker and his team recommend continuing to explore diffusing
materials, although the reduction of light intensity likely is an unavoidable
side effect. What also increases the level of difficulty is that I am looking for a
small solution and one that is suitable for use with a textile structure. Finding
47