The Honeywell HOA1397-002 is a compact reflective optical sensor consisting of an infrared LED paired with a phototransistor. It detects the presence or absence of reflective objects by measuring the intensity of reflected IR light. The phototransistor output switches states (high/low) based on the detected signal, making it suitable for applications like object detection, position sensing, and assembly line automation. Its robust design supports a wide voltage range and industrial temperature conditions.