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Infra_Red Range Finder

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vinci808

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Hi guy , i just like to know how could i replicate a Infra-Red Range Finder
i.e Sharp GD2D12.
I try searching for its equivalent schematic diagram but failed

Thanks for ur help
 

tansis

New Member
Theory of Operation,
http://www.acroname.com/robotics/info/articles/sharp/sharp.html#s1


These new rangers all use triangulation and a small linear CCD array to compute the distance and/or presence of objects in the field of view. The basic idea is this: a pulse of IR light is emitted by the emitter. This light travels out in the field of view and either hits an object or just keeps on going. In the case of no object, the light is never reflected and the reading shows no object. If the light reflects off an object, it returns to the detector and creates a triangle between the point of reflection, the emitter, and the detector.


Different Angles with Different Distances


The angles in this triangle vary based on the distance to the object. The receiver portion of these new detectors is actually a precision lens that transmits the reflected light onto various portions of the enclosed linear CCD array based on the angle of the triangle described above. The CCD array can then determine what angle the reflected light came back at and therefore, it can calculate the distance to the object.

This new method of ranging is almost immune to interference from ambient light and offers amazing indifference to the color of object being detected. Detecting a black wall in full sunlight is possible.

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What the article does not mention is your stumbling block, a fresnel type lens in front of the ccd, returned light from each "angle" appears at a different place on the ccd sensor ,difficult to replicate , the old fashioned way would be to use a small spinning mirror in front of your IR source/reciever.
 
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