D-models are typically used for measurements on objects moving parallel to the axis of the sensor.
The output voltage function for D-model sensors includes a near range where the voltage increases with distance, an optical peak range, and a far range where the output voltage decreases with distance.
Operation at close range results in high sensitivity with a limited measuring range. Long-range operation gives moderate sensitivity with a larger measurement range.
D-type sensors are fast-acting sensors that are ideal for dynamic applications with uniaxial movement, such as those found in actuators, pistons, and valves.