An optical resonator has an internal cavity with an output coupler, an end mirror, and one or more active mirror amplifiers that are arranged in a manner to form a laser radiation propagation path within the cavity which substantially has the form of a star polygon trajectory. The introducer has a trigger wire catheter and four trigger wires and each trigger wire extending in a loop from the trigger wire catheter. The additive can be used in a polyorganosiloxane composition intended for the production of a silicone elastomer with either crosslinks at high temperature under the action of organic peroxides or crosslinks at ambient temperature or with heat by polyaddition reactions in the presence of a metal catalyst. Thus, deterioration of an EL layer due to oxidization can be prevented. 0 at the \u03bbmax, has the change ratio of absorbance at the \u03bbmax in the visible region, specified in the specification; and the inkjet ink set containing at least two black inks having different densities has the relationship among the at least two black inks, specified in the specification. Embodiments of the invention may include a particular endoscopic positioning mechanism for placing an endoscope and an additional treatment device within desired body portions in order to assist in diagnosis and treatment of anatomical diseases and disorders.