Abstract: Disclosed fluid purification systems can comprise a treatment vessel configured to contain a fluid to be purified, a source of ultraviolet radiation with at least 50% of its emitted spectral energy at wavelengths between 315 nm and 400 nm positioned exterior to the treatment vessel, and a portion of a wall of said treatment vessel that is substantially transparent to the ultraviolet radiation emitted by the source of ultraviolet radiation, located so that at least 50% of the ultraviolet radiation propagates through the substantially transparent portion of the wall and is configured to propagate into fluid to be treated within the vessel for the purpose of killing or disabling pathogenic microorganisms in the fluid.

Abstract: Disclosed herein are embodiments of a solar-activated photochemical fluid treatment system, some of which comprise a fluid vessel, a porous enclosure positioned inside of the fluid vessel, a porous enclosure positioned inside of the fluid vessel, a fiber substrate contained within the enclosure, and a semiconductor photocatalyst coupled to the fiber substrate. The fluid vessel can be configured to contain a fluid in contact with the photocatalyst such that the fluid treatment system, responsive to solar radiation applied to the photocatalyst and to the fluid in the vessel, induces photochemical modification of contaminants and living organisms in the fluid. Related methods are also disclosed.

Abstract: Apparatus and methods for the photochemical purification of fluids are disclosed. Fluids containing organic, inorganic and/or microbiological contaminants are treated by photochemical processes in a hybrid photoreactor incorporating a photocatalyst bonded to a light transmissive fiber substrate within at least a portion of the fluid and light sources to illuminate the fluid and photocatalyst. Photochemical processes include photocatalytic oxidation, photocatalytic reduction, photoadsorption, photolysis and photodisinfection. Some aspects of the disclosure include optimization of distribution of photocatalyst within the fluid, optimization of mass transport of contaminants by distribution of randomly-oriented fiber substrate, optimization of photoefficiency by control of light source wavelengths, use of LEDs to achieve optimized light source wavelengths, optimization of light delivery from light sources to fluid, and use of a microprocessor to optimize system performance.

Abstract: A cavity thickness compensated etalon filter. A tuning medium is placed in a Fabry-Perot etalon cavity. The index of refraction of the tuning medium varies as a function of voltage applied across the medium. The etalon is formed of two generally flat substrates disposed substantially parallel to one another. Each substrate has a layer of conductive material within the cavity adjacent the substrate. Each substrate also has a layer of reflective material within the cavity adjacent the substrate. At least one layer of reflective material is only partially reflective so as to enable light to pass into and out of the cavity. Liquid crystal material may be used as a tuning medium in the cavity. In the case of liquid crystal material, the etalon also comprises an alignment layer disposed within the cavity adjacent each substrate to pre-order the liquid crystal material.

Abstract: An ultra-short optical pulse source uses a gain-switched laser diode with a dispersive delay line to compress the optical pulse output from the laser diode, the gain-switched laser diode having particular spectral characteristics. The gain-switched laser diode may be tested by energizing it with a continuous wave signal at or near the lasing threshold level. The resulting spectrum is examined for the presence of satellite spectral intensity features. Those gain-switched laser diodes that exhibit a spectrum having all satellite spectral features below a predetermined level with respect to the intensity of a principal spectral component are selected for use in the ultra-short optical pulse source.