Abstract: A passive Q-switch for a laser system, and a method for its production. The laser is operative at near infrared wavelength region, including the eye-safe region. The Q-switch includes a saturable absorber based on IV-VI semiconductor nanocrystals (NCs), embedded in a polymer matrix. The NCs preferably include lead selenide, lead sulfide, or lead selenide sulfide. The NCs may be surface passivated, and may feature a PbSe/PbS core-shell configuration.

Abstract: Control of a heliostat field (1) in a solar energy plant is provided with a system (6) which controls the alignment of heliostat mirrors (2) in a controlled area of the heliostat field (1) with respect to a selected zone in a target plane (P). The control system (6) comprises a detection device (7) removed from the target plane (P) in the direction of propagation of radiation (R') directed by the heliostat mirrors towards the target plane (P). The detection device (7) has a detection surface (8) facing the radiation (R').

Abstract: A method of delivering guided radiation arriving via a first transparent medium having a first refractive index into a second transparent medium having a second refractive index that is smaller than the first refractive index, comprising: providing a transparent radiation delivery waveguide capable of admitting concentrated radiation and having a longitudinal axis and a third refractive index substantially equal to or greater than the first refractive index and adapted to guide the radiation along the longitudinal axis. The waveguide having a tapered radiation delivery portion of non-circular cross-sectional shape. Mounting the waveguide in optical contact with the first transparent medium so that the radiation delivery portion projects inside the second transparent medium.

Abstract: A laser apparatus of the end pumping kind in which an elongated transparent laser element is mounted in spaced relationship within a tubular waveguide which has a highly reflective inner surface. The arrangement is such that, at least along part of the laser element, the optical distances between different points on the surface of the laser element and the inner contour of the waveguide vary.

Abstract: The disclosure concerns various improvements in a solar energy plant of the kind in which incoming solar radiation is concentrated by a Fresnel reflector, i.e. a field of concentrating mirrors, and the concentrated radiation is focused into a solar receiver. By one improvement a dielectric mirror is provided at a suitable level above the solar collector, to reflect the concentrated solar radiation into the collector. By another disclosed improvement a plurality of non-imaging secondary concentrators arranged in concentric zones is provided intermediary between the dielectric mirror and receiver. By yet another improvement the solar receiver is directly attached to a heat storage system.