Thermal Emission
Infrared radiation modules consist of a micro-machined membrane structure that acts as a broadband source for gas sensing applications. A mems ir emitter generates light by resistive heating of a thin film element suspended above a silicon substrate. This configuration reduces the thermal mass to enable rapid modulation frequencies which exceed those of traditional incandescent light bulbs.
Electrical Characteristics
Pulse width modulation controls the spectral output of the mems ir emitter by varying the duty cycle of the applied voltage. Lower thermal mass allows for high frequency pulsing that minimizes power consumption during measurement cycles. Peak intensity drops if the drive current exceeds the manufacturer specifications because the membrane temperature approaches the physical limit of the material bond.
Mechanical Construction
Vacuum packaging improves the efficiency of a mems ir emitter by preventing convective heat loss to the surrounding gas medium. Thin film resistors sit on a ceramic or silicon nitride support membrane to achieve high temperatures at minimal wattage. This geometry limits the radiant surface area while optimizing the optical coupling to the sensing path.
Measurement Accuracy
Calibration procedures for the mems ir emitter require a reference detector to account for emissivity drift over time. Aging effects occur when metal atoms migrate across the membrane surface under continuous thermal stress. Stability remains high provided the power supply regulates the voltage within a tight tolerance during the entire duty cycle.
