Temperature Measurement on Micromachined IR Bolometers Using an Infrared Microscope

Abstract

Thermal properties are critical to the performance of micromachined silicon bolometers. In order to verify thermal models of the device, a means of measuring the local temperature distribution over the element is required, as it is heated by passing current through a thin film titanium meander. Because of the very low thermal mass of the membrane a non-contact method of temperature measurement is needed. Most conventional thermal imaging systems operate in the wavelength range 5-15 μm and offer poor spatial resolution but in this work an infrared microscope, operating at shorter wavelengths, was used. The microscope comprises an objective lens which focuses radiation onto a cooled (77K) cadmium mercury telluride focal plane array sensitive over the range 800 nm to 2500nm. For this application a bandpass filter centered at 2150 nm was used. Good agreement was obtained between finite element modeling of the temperature distribution, using ANSYS, and the measured data.