Digital Signal Processing Reference
In-Depth Information
Figure 13.9
Sharp IR Ranging Module.
Far Object
Scattered
Reflection
Near Object
Lens
Lens
Position
Sensitive
IR Detector
IR LED
Figure 13.10
Operation of
Sharp IR Ranging Module.
As shown in Figure 13.10, internally the GPD2D02 contains an IR LED and a
position-sensitive IR detector. The IR LED transmits a modulated beam of
infrared light. When the light strikes an object, most of the light will be
reflected back to the LED. Since no surface is a perfect optical reflector,
scattering of the IR beam occurs at the surface of the object and some of the
light is reflected back to the position sensitive detector. By comparing the near
and far object beams shown in Figure 13.10, it is apparent that the position at
which the scattered reflected IR beam hits the detector is a function of the
reflection angle.
