This popular sensor made by Sharp produces an
analog output that varies from from 2.5V at 20cm to 0.4V at 150cm.
Based on "typical values" from Sharp, the formula to translate
SensorValue into Distance (the formula is only valid for a SensorValue
between 80 to 490) is:
Distance (cm) = 9462/(SensorValue - 16.92)
This sensor can find the distance to objects that present a very narrow
edge such as a wall at a very sharp angle.
Note: The output of this sensor will vary from unit to unit, and based
on the characteristics of the target (reflectance, size, direction
of motion, object alignment, ...). If you find that you are not getting
good results with the standard formulas, you may want to derive your
own formula to better characterize your situation.
We also carry two other Sharp distance sensors for longer distance ranges.
3520 ¡V Sharp Distance Sensor GP2Y0A21YK0F (4-30cm)
3521 ¡V Sharp Distance Sensor GP2Y0A02YK0F (10-80cm)