Impact of environmental parameters on the emission intensity of micromachined infrared sources

Micromachined infrared (IR) sources play an important role in the design of miniaturised chemical analysis systems. The reliability and resolution of non-dispersive IR detection systems - among other factors - critically depends on the stability of the emission coming from micromachined IR sources. In the present investigation, the impact of environmental parameters on the emission intensity of such sources has been investigated and rationalized in terms of a thermal resistor model. Our results show that the emission of state of the art IR sources is affected to a non-negligible extent by changes in ambient temperature and humidity as well as by variable airflows in the vicinity of the emitting surface. We further demonstrate that proper packaging involving IR transparent windows can significantly reduce the impact of these environmental effects. In addition, ambient-temperature compensation methods need to be employed to arrive at a stable IR emission.