Light Delivery Methods Research Articles

APPLICATIONS OF FAR-RED LIGHT EMITTING DIODES IN PLANT PRODUCTION UNDER CONTROLLED ENVIRONMENTS

ISHS International Symposium on Advanced Technologies and Management Towards Sustainable Greenhouse Ecosystems: Greensys2011 APPLICATIONS OF FAR-RED LIGHT EMITTING DIODES IN PLANT PRODUCTION UNDER CONTROLLED ENVIRONMENTS

Hybrid lighting systems: Performance and design

Hybrid lighting systems simultaneously deliver daylight and electric light into the core of a building where they are combined and distributed via luminaires. The systems have only been developed in the last few years and accordingly there is little accumulated experience of light delivery or design methods. This paper presents measured data for a commercially available hybrid system located in the United Kingdom. The performance of the hybrid system is compared with that of a tubular daylight guidance system. The results are discussed in the context of use of the systems for a range of sky conditions. Design recommendations and limitations to address knowledge shortfalls for hybrid systems are put forward.

Spectrally Selective Light Induced Release from Gold Coated Liposomes

In the interest of creating functional nanostructures to address unmet medical needs for controlled delivery and release, we recently presented liposome-supported plasmon resonant gold nanoshells (Troutman et al., Adv. Mater. 2008, 20, 2604-2608). These composite structures are degradable into components of a size compatible with renal clearance, potentially enabling their use as multifunctional agents in imaging, diagnostic, therapeutic, and drug delivery applications. The liposome allows for the encapsulation of substances, including diagnostic and therapeutic agents, while the plasmon resonant structure facilitates the rapid release of encapsulated contents upon laser light illumination using a wavelength corresponding to the resonance band. Furthermore, the resonance of these gold-coated liposomes is tunable in the near-infrared range. Using this tunability, we achieved spectrally selective content release using two laser wavelengths, in which full content release occurs for liposomes spectrally matched with the illumination source and minimal release occurs for liposomes not matched with the source. Also, spectrally selective release is accomplished through the use of multiple, low intensity laser pulses, ensuring that illumination affects only the gold-coated liposomes and avoids heating the surrounding media; this observation is supported experimentally and through modeling of the heat equation. Within the context of biological and medical applications, gold-coated liposomes may enable the spectral, spatial, and temporal control of release of multiple agents from liposome carriers by means of a physiologically safe light-delivery method.

Hybrid recording on bit-patterned media using a near-field optical head

We have demonstrated hybrid recording on magnetic bit-patterned media by a near-field optical head with plasmon probe. The near-field plasmon probe nanobeak that uses a triangular metallic plate with a three-dimensionally tapered apex can provide a highly efficient optical spot as small as 16 nm × 20 nm. The bit-patterned media consist of a Co (0.3 nm)/Pd (0.7 nm) multilayer of 20-nm-thick magnetic nanodots each with a diameter of 20 nm and a period of 30 nm. We confirmed magnetic single-dot recording on the Co/Pd bit-patterned media. Hybrid recording simulation results suggest that hybrid recording on bit-patterned media can achieve significant data-density recording, even when the magnetic dot size is less than 5 nm. For practical use, we made a prototype of nanodot circularly aligned Co/Pd bit-patterned media, and also demonstrated light delivery method using either solid immersion optics or an optical fiber.

Light delivery for whole-bladder photodynamic therapy

The dose-response behaviour in total-bladder photodynamic therapy (PDT) is calculated for both the argon-pumped dye laser (630 nm) and the argon laser (488/514.5 nm) wavelengths delivered in two light-delivery methods by using an isotropically emitting fibre placed in the centre of the bladder cavity. Method 1 assumes that the bladder is filled with a perfectly clear medium. In method 2, this is replaced with a perfectly scattering medium. Two assumptions are made: that the bladder is a perfect sphere whose wall thickness is much smaller than its radius, and that there is refractive-index matching between the bladder tissue and the liquid filling the bladder cavity. The optical properties of healthy dog bladder, measured in vitro, are used in the one-parameter diffusion approximation to the radiative transport equation to calculate the distribution of the light fluence rate inside the bladder wall. The integrating-sphere effect of this geometry is explicitly accounted for. Threshold fluences for tumour necrosis are obtained from previous animal experiments. The results confirm that the argon laser provides the method of choice to treat widespread superficial bladder cancer, albeit with a greater risk of damage to the healthy lamina propria. Method 2 predicts better efficiency than method 1, provided that the tumour is superficial. Possible reasons for differences between calculated dose-response curves and clinical results are discussed. The analysis suggests a simple and practical method to assess the clinical dose-response curve from a knowledge of: (a) the local, incident light-dose during (focal) treatment; (b) the resulting depth of PDT-necrosis; and (c) the optical properties of diseased human-bladder tissue.