- A 2 stack two color Quantum Well Infrared Photodetector (QWIP) for simultaneously detection of Long Wavelength InfraRed (LWIR) and Near InfraRed (NIR) radiation is demonstrated. The LWIR sensor is based on a regular GaAs/AlGaAs QWIP, while the NIR sensor is based on a strained InGaAs/GaAs multi quantum wells structure. Optical and electrical measurements of the NIR detector and the inclusive device are presented and discussed. Aspects of the monolithic thermal imaging and see spot system are considered. System performance prediction is calculated based on the FLIR92 method, using MATLABR as a platform to the numerical calculations. The system calculations are based on a conversion method of the laser radiation at the target to a thermal like radiation, enabling calculation of the whole system parameters. This method allows one to predict the maximum range of the observing system from the target that still allows detection of the laser spot over the thermal picture.