# IR Absorption #detection-technology #sensor #infrared Infrared (IR) absorption is a detection technology that measures gas concentration by detecting the absorption of specific infrared wavelengths by target gas molecules. ## Principle - Gas molecules absorb specific IR wavelengths - Absorption is proportional to gas concentration - Uses Beer-Lambert law - Selective detection based on molecular structure ## Advantages - Selective detection (minimal cross-sensitivity) - No oxygen required - Not susceptible to catalyst poisoning - Long sensor life - Suitable for many hydrocarbon gases ## Applications - Methane detection - Hydrocarbon gas detection - Open path detection - Point detection ## Types - **Single Wavelength**: Measures absorption at one wavelength - **Dual Wavelength**: Compares absorption at two wavelengths (reference and measurement) - **Open Path**: Detects gas clouds over distances - **Point Detection**: Measures at specific location ## Limitations - Requires IR-transparent gases - Some gases don't absorb IR well - Can be affected by environmental conditions - More expensive than catalytic sensors ## Comparison with Catalytic Sensors - IR: Selective, no oxygen needed, longer life - Catalytic: Lower cost, detects all flammable gases, requires oxygen ## Related Concepts - [[Methane]] - [[Open Path Detection]]