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Microlens arrays can improve light transmittance in optical devices or enhance the photoelectrical conversion efficiency of photovoltaic devices. Their surface morphology (aspect ratio and packed density) is vital to photon management in solar cells. Here, we report a 100% packed density paraboloidal microlens array (PMLA), with a large aspect ratio, fabricated by direct-write UV laser photolithography coupled with soft imprint lithography. Optical characterization shows that the PMLA structure can remarkably decrease the front-side reflectance of solar cell device. The measured electrical parameters of the solar cell device clearly and consistently demonstrate that the PMLA film can considerably improve the photoelectrical conversion efficiency. In addition, the PMLA film has superhydrophobic properties, verified by measurement of a large water contact angle, and can enhance the self-cleaning capability of solar cell devices.

Distributions of the optical field in a solid immersion lens recording system are calculated for higher-order radially polarized modes of the incidence. Results show that two higher-order radially polarized modes of R-TEM(11) (* )and R-TEM(21) * are useful to near-field optical recording, but further higher-order modes such as R-TEM(31) (* ), R-TEM(41) (* ), and R-TEM(51) (* ) are not useful due to the strong side-lobe intensity. Compared with R-TEM(01) (* ) beam focusing, the full width at half-maximum of the recording spot is decreased markedly and the focal depth is increased substantially by using R-TEM(11) (* )beam focusing. The effect of the beam width of the R-TEM(11) (* ) mode is also discussed.

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For the correlated color temperature (CCT) of a light source to be estimated, a nonlinear optimization problem must be solved. In all previous methods available to compute CCT, the objective function has only been approximated, and their predictions have achieved limited accuracy. For example, different unacceptable CCT values have been predicted for light sources located on the same isotemperature line. In this paper, we propose to compute CCT using the Newton method, which requires the first and second derivatives of the objective function. Following the current recommendation by the International Commission on Illumination (CIE) for the computation of tristimulus values (summations at 1 nm steps from 360 nm to 830 nm), the objective function and its first and second derivatives are explicitly given and used in our computations. Comprehensive tests demonstrate that the proposed method, together with an initial estimation of CCT using Robertson's method [J. Opt. Soc. Am. 58, 1528-1535 (1968)], gives highly accurate predictions below 0.0012 K for light sources with CCTs ranging from 500 K to 10⁶ K.