An Infrared (IR) based security system is a technology that utilizes infrared light to monitor, detect, and safeguard against unauthorized access or intrusions into a specified area. It operates on the principle of detecting changes in the IR radiation or light emitted by objects in its field of view. Here's a detailed description of how an IR-based security system works and its key components:

1. IR Sensors/ Detectors:
• IR sensors or detectors are the core components of this security system. These sensors can be passive or active, each with its own function:
• Passive Infrared (PIR) Sensors: These sensors detect changes in heat radiation, usually emitted by moving objects. They are commonly used in motion detection applications and can trigger alarms or lights when movement is detected.
• Active IR Sensors: These sensors emit infrared light and then detect its reflection. They are often used in proximity detection, such as for automatic door openers.
2. IR Transmitters:
• Active IR-based security systems use IR transmitters to emit infrared light. These transmitters emit a continuous or modulated IR signal, and the system looks for interruptions or changes in the reflected signal.
3. Control Unit:
• The control unit is the brain of the IR-based security system. It processes the information received from the IR sensors and makes decisions based on predefined criteria. It can activate alarms, notify authorities, or perform other security-related actions.
4. Alarms and Notifications:
• When the system detects unauthorized access or any abnormal event, it can trigger alarms. These alarms can be in the form of sirens, lights, or notifications sent to a monitoring station or the property owner.
5. Integration with Other Systems:
• Modern IR-based security systems often integrate with other security systems, such as CCTV cameras and access control systems, to provide a comprehensive security solution.
6. Applications:
• IR-based security systems find applications in various scenarios, including:
• Home security: Detecting intruders and triggering alarms.
• Perimeter security: Protecting the boundaries of a property.
• Industrial security: Monitoring access to restricted areas within factories and warehouses.
• Proximity sensing: Opening automatic doors when someone approaches.
• Motion detection: Activating lighting when motion is detected in a dark area.
• Environmental monitoring: Detecting fires or smoke in buildings.
7. Advantages:
• Cost-effective: IR-based systems are often more affordable than other security technologies.
• Reliability: They are highly reliable and immune to some common false alarms.
• Low power consumption: Many IR sensors are energy-efficient.
8. Limitations:
• Limited range: The effective range of IR sensors is generally limited.
• Susceptibility to interference: Environmental factors, such as temperature changes, can affect the accuracy of some IR sensors.
• Limited functionality: IR-based security systems primarily detect motion and presence; they may not be suitable for complex security needs.

In summary, an IR-based security system offers an effective and cost-efficient means of monitoring and securing areas against unauthorized access or detecting abnormal events. Depending on the specific application and the type of IR sensors used, these systems can be an essential component of a comprehensive security strategy.