KJT high-precision color mark sensor combines the characteristics of small spot size and fast response, and can complete high-speed contrast detection work. The S50PM is capable of effectively detecting contrast differences between multiple colors on a variety of surfaces over a range of 50 gray levels. The adjusted white light source can be focused into a 2.5-3mm spot and directed towards the target. The diffuse light returning to the sensor is measured. The digital output changes state when its level equals or exceeds the threshold. Because the sensor responds quickly, it is suitable for high-speed applications. Sensor provides digital output and is automatically configurable NPN and PNP. A PLC or computer can be used to monitor the status of digital output signals.