Subwavelength metal apertures significantly enhance single molecule fluorescence signaling systems, but require
efficient illumination and collection optics. On-chip micromirror structures offer a way to markedly improve the
coupling efficiency between such subwavelength metal apertures and the external fluorescence illumination and
collection optics, which in turn greatly simplifies several aspects of instrument design including optics,
optomechanics, and thermal control. Modeling and experimental verification of the gains in illumination and
collection efficiency for subwavelength metal apertures leads to a micromirror design that is both highly efficient
yet also manufacturable. A combination of ray-based and finite-difference-time-domain models is used to optimize
conical micromirrors colocated with subwavelength metal apertures for the case where the illumination light
interacts strongly with the micromirror and the collection optics have modest numerical aperture (NA~0.5).
Experimental methods employing either freely diffusing or immobilized dye molecules are used to measure the
illumination and collection efficiencies of fabricated micromirror prototypes. An overall fluorescence gain of
~100x, comprising a 20x improvement with flood illumination efficiency together with a 5x improvement in
collection efficiency, are both predicted and experimentally verified.
The series electrical nature of the multi-junction solar cell is both the source of its desirable overall efficiency and of its sensitivity to spectral balance. Owing to the series connection of the spectrally selective junctions, variations in the spectra of the solar input, optical transfer function, and cell quantum efficiency have significant impact on annual energy production despite being effectively indistinguishable in instantaneous power output. This paper will outline spectral filtering approaches for experimental characterization, and spectral simulation methods for estimating annual energy production. We will also present system level design to optimize for annual energy production.
The Levelized Cost of Energy (LCOE) takes into account more than just the cost of power output. It
encompasses product longevity, performance degradation and the costs associated with delivering energy to the grid tie
point. Concentrator optical design is one of the key components to minimizing the LCOE, by affecting conversion
efficiency, acceptance angle and the amount of energy concentrated on the receiver.
Optical systems for concentrators, even those at high concentrations ( >350X) can be designed by
straightforward techniques, and will operate under most circumstances. Adding requirements for generous acceptance
angles, non-destructive off-axis operation, safety and high efficiency however, complicate the design. Furthermore, the
demands of high volume manufacturing, efficient logistics, minimal field commissioning time and low cost lead to quite
complicated, system level design trade-offs. The technology which we will discuss features an array of reflective optics,
scaled to be fabricated by techniques used in the automotive industry. The design couples a two-element imaging system
to a non-imaging total internal reflection tertiary in a very compact design, with generous tolerance margins. Several
optical units are mounted in a housing, which protects the optics and assists with dissipating waste heat.
This paper outlines the key elements in the design of SolFocus concentrator optics, and discusses tradeoffs and
experience with various design approaches.
Bragg selectivity in volume holography can be exploited to store many holographic pages within the same physical volume. The detailed character of this Bragg selectivity is also responsible for the crosstalk among stored pages and is governed by the 3D envelope function of the volume hologram. Other workers have discussed these crosstalk effects in detail. In this paper we discuss the effect of reference beam apodization on the angular selectivity of photorefractive volume holograms. Apodization using phase-only beam forming is studied and we focus on the use of apodization during hologram retrieval. The trade-offs among storage capacity, information density, and noise are discussed for both the apodized and unapodized configurations. The presence of conventional hologram crosstalk as well as effects due to material absorption and recording angle jitter are included.