Pyroelectric detectors are suitable for this application with high temperature stability, excellent signal to noise and low cost.
A pyroelectric crystal is distinguished by having an atomic structure that will move slightly in response to a change in temperature, rearranging the electric charge within the solid generating a voltage which can be measured using a set of electrodes on the crystal surface.
LASER COMPONENTS is a manufacturer of pyroelectric detectors. The devices are manufactured in standard TO style packages and have long expected lifetimes making them suitable for this fit and forget application.
