Volume 4: Optical Sensors covers various approaches used for modelling and simulation of different types optical sensors such as fibre optic, surface Plasmon resonance, Fabry-Perot interferometer, transmittance in the mid-infrared region, luminescence based devices, etc. Approaches used for design and optimization of optical systems aimed for remote gas sensing and gas analysis chamber for NDIR spectral range are discussed as well. The description of multiscale atomistic simulation of hierarchical nanostructured materials for optical chemical sensing is also included in present volume. This 5 volume reference work covering simulation and modelling will serve as the perfect complement to Momentum Press’s 6 volume reference works Chemical Sensors: Fundamentals of Sensing Materials and Chemical Sensors: Comprehensive Sensor Technologies, which present detailed information related to materials, technologies, construction and application of various devices for chemical sensing.