Most modern automatic focus cameras use the parallax resulting from the differing locations of a beam generating emitter and an imaging detector as the basis for estimating the range to the target (subject). The LED is usually a powerful AlGaAs type emitting at 880nm, and pulse currents as high as 10 Amps are not uncommon. Because the detector is positioned at an offset (also called baseline) from the emitted beam, the position of the image of the beam (as reflected by the photographic subject) varies as a function of range. Many of these modules incorporate Position Sensing Diodes (PSDs, also called Lateral Effect Diodes), but dual photodiodes work just as well. The 2 signals provided by the detector are used to derive and estimate of range to the target or photographic subject. The most commonly used signal processing method is called ratiometric range measurement. Hamamatsu, Sharp, and Ricoh are the big suppliers. Sharp offers a module for use outside of cameras. Their US organization is based in Camas, WA.