Pyroelectric infrared arrays and their applications

For different applications the use of uncooled thermal infrared detectors is often a low-cost alternative to the cooled semiconductor detectors. By the development of a large number of novel detector technologies the thermal and spatial resolution of the thermal detectors could be improved considerably. On the basis of the pyroelectric material lithium tantalate (LiTaO3) a cheap and flexible detector technology was developed for the design and manufacturing of user-specific arrays even at small batch quantities. The possibilities of this technology are described by the example of newly developed linear arrays with 128 responsive elements of different sizes (pitch 100 mu m) and 256 responsive elements (pitch 50 mu m) as well as a two-dimensional array with 16 x 8 responsive elements. The given detector properties of the arrays clearly show that the achieved detector properties meet the demands of many applications. Responsive elements having a thickness of less than 5 mu m can be produced by the use of ion-beam etching for the structuring of the pyroelectric chips. In connection with a low-noise CMOS read-out circuit, NEP-values lower than 1.5 nW were obtained by it at a chopping frequency of 128 Hz. The effective capacity of the detectors is illustrated on the basis of two detector applications in devices for the two-dimensional temperature measurement and in a spectrometer.