Optical chemical sensor OPTISENS allows the detection of chemical warfare agents, such as Sarin, Soman, and VX, in gas as well in liquid phase. The sensor instrument detects extremely low concentrations of the chemical warfare agents in a short time. Two instrument designs are possible, without or with optical fibers. In the first case, the sensor chip is placed directly on the instrument and in the second case the sensor chip is placed on the end of the optical fibres and connected to the instrument through them. On the request, more optical fibers can be connected to the one instrument.