Use of optical systems in hazardous locations can result in ignition of surrounding explosive atmosphere. The conducted research work allowed to propose three protection concepts. The primary protection concept - inherently safe optical radiation - consists in use of optical radiation with power, energy or irradiance incapable of causing ignition of surrounding explosive atmosphere. However, the arbitrary determination of values of these parameters is considered as
excessively rigorous. The work presents the proposed protection concepts in relation to zone classification. The author describes his own method to determine safe values based on probability mathematics that can be used not only to derive these values, but also to compare different measurement procedures and, as well, different tests set-up.
Uncomplicated structure and low costs have caused an immense increase in the applications of reflective optical fiber sensors. The growing interest demands more precision and reliability from the sensors. At the same time the development of microprocessing resulting in increased computing power and computer speed allows to create and simulate increasingly complex systems or 3D measurement structures. Using these possibilities, the paper presents the results of a computer simulation of a fiber optic reflective structure. Special attention is paid to the effect of deflection changes in the reflective surface and to the diffuse reflection from the analyzed surface.