Single light source photoelectric scanning system
Single light source system use the condenser lens LED light source and photocell array.
Advantage: Due to the light source and photoelectric sensor is composed of a single piece of electronic components, four-way linear error and amplitude error between the output signal is very small, hence it is easy to obtain high accuracy in position error within one signal period.
Disadvantage: Cannot use in slimline scale housing linear scale due to the big LED dimension.
Four light source photoelectric scanning system
Four light source system use four small infrared ray LED light source and four small photoelectric receiving tube.
Advantage: Four light source system can use in slimline Scale housing .
Disadvantage: Due to the light source and photoelectric sensor is composed of four different electronic components. Four-way linear error and amplitude error between the output signal is obvious. So the position error within one signal period is bigger than the single light source.
We will not suggest use four light source photoelectric scanning system into high accuracy linear scale(0.1µm or 0.01µm). on the other hand, user will not find the difference of position error within one signal period between one light and four light source system if use the 0.5µm or 1.0µm resolution scale.