Optical performance of progressive addition lenses (PALs) with astigmatic prescription

The progressive addition lens (PAL) is a spectacle lens design with progressive refractive power changes across the lens surface to provide sharp vision at different viewing distances for patients with reduced accommodative strength. It has gained in popularity not just for presbyopic patients, but also patients with occupational (office, driving, or digital device) and therapeutic (e.g., myopia control) needs. However, despite the increasing prevalence of astigmatism in adults > 40 years old who rely on PAL correction, no metric is available to reflect the optical variation in PALs with astigmatic prescriptions. Based on recent studies, four novel optical metrics sensitive to variation of refractive power across the lens surface of PALs have been developed. These metrics were used to compare the optical performance of PALs of various prescriptions, designs, and manufacturers. For each lens, the refractive power profile was first measured with a Moire-deflectometry-based instrument.The data was then exported and analyzed using a two-dimensional error map for each of the four metrics. The results revealed significant impacts of astigmatic prescription, providing evidence for the usefulness of these metrics in quantifying the optical performance of PALs for patients with astigmatic prescriptions.

Enhancement of Organic Solar Cell Performance by Utilizing Cupper Phthalocyanine

An approach for improving the photoelectrical conversion efficiency of hetero-junction solar cells based on lead phthalocyanine, by incorporating cupper phthalocyanine with co-evaporation technique into the active layer has been reported in this work, the effect of adding cupper phthalocyanine (CuPc) have been studied. The morphological, optical, and electrical properties of PbPc active layer and blend have been reported. Atomic force microscope study shows a change in the roughness, UV-VIS Spectroscopy revealed that the absorbance of PbPc films increases in the blend case and has a main Q-band at wavelength 748 nm and the electrical study showed a change in (I–V) characteristics, the photoelectrical conversion efficiency (PCE) of solar cells increases. The photovoltaic parameters are discussed based on the morphology and optical variation of the active layers.

Recent advances in VO2-based thermochromic composites for smart windows

Vanadium dioxide (VO2) is a well-known thermochromic material since it exhibits a notable optical variation in the near-infrared region from transmitting to reflecting upon the semiconductor-to-metal phase transition (SMT).

Phytoplankton community dynamic detection from the chlorophyll-specific absorption coefficient in productive inland waters

Aim: In this research, we investigated the spectral variability of the specific phytoplankton absorption coefficient, a*φ, measured in a tropical meso-to-hypertrophic reservoir, aiming to find spectral features associated with the chlorophyll-a (chla) and other accessory pigments present in different phytoplankton species. Methods To accomplish this research, two fieldworks were carried out in different seasons in order to report a high bio-optical variation. Phytoplankton absorption coefficient, aφ, and chla concentration were measured in laboratory to estimate a*φ. Results The outcomes have indicated that there is a remarkable phytoplankton community dynamic as spatially as seasonally. Chla absorption features were well-defined at 440 nm and 675 nm. Conclusions All the a*φ spectra exhibited the absorption peak around 630 nm associated with phycocyanin pigment present in cyanobacteria. Some spectra have shown a peak at about 460 nm, which is related to chlorophyll b and chlorophyll c (chlb and chlc, respectively) found in different phytoplankton species. In turn, absorption features of carotenoids around 490 nm also were identified, however, well defined just in curves measured in austral autumn. Such spectral features are found in phytoplankton groups already identified in the study area such as Chlorophyceae, Bacillariophyceae, Cyanophyceae, Conjugatophyceae, Chrysophyceae, among others. We expect that the results are useful in researches about remote sensing of phytoplankton and eutrophication in reservoirs.

Simultaneous luminescence modulation and magnetic field detection via magneto-optical response of Eu3+-doped NaGdF4 nanocrystals

Magnetic confinement of f electrons wave functions and magnetic field assistant cross relaxation mechanism was firstly built for optical variation.