Make your own sensor using the IR emitter/detector:
There is an infrared emitter and detector included in the lab kit -
use them to make a simple custom sensor for a hypothetical project
(imagine a configuration that would be useful for a kinetic sculpture
or other interactive setup)... you can hook them up in a circuit that
looks like this:
The detector is actually a phototransistor. Like diodes, all transistors
are light-sensitive. Phototransistors are designed specifically to take
advantage of this fact by exposing the base region. So, light striking the
base replaces what would ordinarily be a bias voltage applied to the base
leg of a regular transistor.
This is the emitter datasheet:
http://www.sparkfun.com/datasheets/Components/LTE-302.pdf
And this is the detector (it's the one with the red paint on top):
http://www.sparkfun.com/datasheets/Components/LTR-301.pdf
Optical sensors can be used either intrinsically (where the optical path
is not interrupted but modified internally), or extrinsically where the
intensity of light is modulated by moving an obstruction into the light path.
The data gloves made for VR simulations are good examples of instrinsic
optical sensing, as the modulation of light through (lossy) fiber-optic
cable is used to determine finger flexion. Old (non-optical) mice are examples
of extrinsic optical interfaces, as the IR light is interrupted in a
quadrature scheme in order to determine motion and direction - see
how a mouse works
for more info.
Optical sensors have been used in many installations, one example is Christopher
Janney's Soundstair (1977), an instrument that transforms an existing stairway
into a musical staircase (each step becomes a musical note). With various
mechanical configurations, they can sense range, tilt, rotation, presence, water level,
etc. and trigger or control many things. Be creative, and demonstrate integrating
and applying optical sensing to make a meaningful and well understood measurement.
