ESA Certified Alarm Technician Practice Exam

The pattern detected by a PIR sensor is influenced by what aspect of its design?

1. Hardware composition

2. Optics

3. Software configuration

4. Sensor calibration

The correct answer is: Optics

The correct answer is based on the role of optics in the functionality of a PIR (Passive Infrared) sensor. PIR sensors detect heat emitted by objects, typically in the form of infrared radiation. The design of the optics, including the lens system, plays a crucial role in shaping the detection pattern of the sensor. The optics used in a PIR sensor can significantly influence the field of view, the distance at which the sensor detects motion, and the sensitivity to object movement across its zone of detection. Different lens designs can create varied detection patterns, such as narrow or wide fields of view, allowing the sensor to be tailored to specific applications. For instance, a Fresnel lens, which is commonly used in PIR sensors, breaks down the lens surface into several smaller segments, allowing the sensor to detect a wider area while maintaining good sensitivity. The shaping of the optics directly affects how well the sensor can pick up changes in temperature from moving objects in its vicinity, making it critical for system effectiveness. While hardware composition, software configuration, and sensor calibration are important aspects of sensor operation, they do not fundamentally alter the pattern detected in the same way that optics do. Optics is specifically designed to affect the detection range and area, underscoring why this aspect