Light Sensor

 

   The Light Sensor has 2 light emitting diodes (LEDs).

       ♦   One is the actual sensor, a photodiode (LED at top), which receives light and is used to measure its intensity.

 

       ♦  The other is an ordinary LED (one at bottom), which illuminates a surface so the first LED can measure the amount of light being reflected from it.

 

   The diodes should be placed about 1 cm from the surface and pointed straight toward the surface.

 

   The light sensor can be used to measure either ambient or reflected light

 

       ♦   Ambient light is the light available around the robot; it is not created by the robot. It is the light begin measured when the Generate Light option

           is not selected. This is useful to detect when light in a room is turned on or to search for a light source.

 

       ♦   The Generate Light option is used to measure reflected light . This will turn on the small light on the front of the sensor, and the sensor will

            measure reflected light, which is the amount of light bounced back from an object close to it. This is useful for following a line or identifying

            objects.

   Calibrating the light sensor

       ♦   This is accomplished by placing the sensor over a piece of black tape (for example) and measuring the reflected light.

       ♦   Then move the sensor off of the tape and measure the reflected light.

       ♦   Take the average of the readings - this will be the threshold point