The Luminescent Solar Concentrator (LSC) consists of a transparent plate with solar cells on one or more sides. The incoming sunlight is absorbed by the luminescent dyes or particles, which are embedded in the transparent plate or applied in a film on the top or bottom of the transparent plate. The absorbed light is re-emitted at a longer wavelength, and part of the re-emitting light is trapped in the transparent plate by total internal reflection (TIR). Then the solar cells attached to the edges of the transparent plate would collect the light and convert it to electricity. However, the luminescent dyes or particles used in the conventional LSC still suffer from reduced efficiencies and lifetimes, then the inorganic phosphors with relatively high quantum yields, good absorption properties and longer lifetime could be alternative materials used in the structure. In this study, the ray-tracing simulation is used to investigate the optical characteristics of the LSC with the inorganic phosphors embedded film on the top or bottom of the transparent plate. The simulation results will also be used to study the loss mechanisms in the LSC with inorganic phosphors embedded film.
Due to the advantages, such as high efficiency, power consumption reduction, no mercury, pure saturated color, high reliability and long lifetime, the solid-state lighting based on light-emitting diodes (LEDs) has become very popular at this stage. In the lighting applications such as spot lighting, downlighting, architectural and show lighting, the colortunable properties with collimating beam of LEDs are highly demanded. The color–tunable lighting is easily achieved using multi-colored LEDs instead of inefficient color filters. However, the applications of multi-colored LEDs usually appear the undesirable light patterns such as color separation or color fringes. At the meantime, the use of TIR (total internal reflection) lens for multi-colored LEDs to collimate the light from the LEDs with different color will introduce seriously undesirable artifacts. Thus, a periodic microstructure surface on the top surface of the TIR lens would be used to reshape the light from the different colored LED chips in the multi-colored LEDs, and then decrease the color separation and color nonuniformity. In this study, the TIR lens with periodic microstructure surface on the top surface would be used to collimate the light from multi-colored LEDs with low color separation or color fringes. The analysis of color enhancement and collimation features of the multi-colored LEDs with different periodic microstructure on the top surface of the TIR lens is presented.
In this study, the design of the projector type headlamp using LEDs with different structure parameters is proposed. The
ellipsoidal reflector with different major and minor axis would contribute different aperture and focal lengths of the
ellipsoidal reflector, and then collimate the light to the converging lens. With specific converging lens and metal-based
baffle plate in the projector type headlamp system, we systematical analysis of the ellipsoidal reflector in the projector
type headlamp. The systematical analysis of the ellipsoidal reflector can be a reference to design a projector type
headlamp with compact size and high photometry performance.
In this study, multivariate data analysis, especially partial least squares regression (PLSR), is applied to analyze the near infrared absorbance spectra of fruit samples in order to acquire the inner qualities without destroying the samples. The calibration models have been established for the samples with raw data, first order derivative and second order derivative treatments, respectively. In the meantime, the models have been verified by using cross validation method. As anticipated, a model with higher correlation coefficient (r) and lower root mean square error of calibration (RMSEC) is preferred for both calibration and cross validation. The results reveal that the calibration models with second order derivative treatments have higher correlation coefficient, coefficient of determination, as well as lower RMSEC. Furthermore, the calibration models have been optimized by selecting partial wavelengths as new variables based on absorbance spectra and regression coefficient. The reasons why the calibration models are improved might be suitably cutting off partial wavelengths causing noises in the model.