Abstract: Standard GaAs/AlGaAs quantum well infrared photodetectors (QWIP) have been seriously considered as atechnological choice for the 3^rd generation of thermal imagers in the long wave infrared band (LWIR) for some time. Alternative technology like MCT (HgCdTe) was the technology choice of the 2^nd generation because of its high quantum efficiency. In the paper, measurements on the QWIP technology will be presented and a comparison with alternative technology will be done.