Alexander Graf

Review of micromachined thermopiles for infrared detection

During the last few years, thermopiles have come increasingly under the spotlight of commercial infrared sensing. This growing interest has motivated us to write an overview of micromachined thermopiles. The first part deals with the Seebeck effect and discusses the most important physical parameters with their interactions. We also describe the main noise sources and give a derivation of the figures of merit and their relevance for thermopile detectors. In the second part, a number of material systems, techniques and micromachined structures are discussed on the basis of different examples. We explain the motivation behind miniaturized thermopile detectors and give a functional explanation of physical interrelations. Finally, different applications are presented and discussed in terms of their future potential.

System Design and Analysis Concept of a Highly Adaptable NDIR Sensor for Gas Analysis

In this paper we present a novel kind of spectroscopic gas sensor. The infrared sensor system is based on the commonly known NDIR system approach. But in contrast to the specific character of these sensors, we use spectrally overlapping broad-band filters and a modulated infrared source to measure a gas mixture. Due to the particular design, detector channels can be reduced and the sensor can be used more flexible. The theoretical concept of the ANDIR sensor system is briefly introduced before we will concentrate on the analysis algorithm and measurement results.