In this paper, the bicubic spline interpolation and high-order polynomial methods were used to optimize the edge thickness of negative blended lenticular lens for patients having high myopia and astigmatism, which are large thickness and weight. For -8D lens with -2D cylinder in 180° axis, based on the setting a valid optical area, the outside area of the blended lenticular lens were designed . The optimized lenses were processed by CNC machine, measured and analyzed. The central optical area obtained via bicubic spline interpolation method is 48.98% greater than high-order polynomial method. The maximum thickness obtained using high polynomial method is 0.62% less than that obtained via bicubic spline interpolation method, which is 17.40% less than the original surface in 180° axis. The edge thickness under high polynomial method is 9.60% larger than bicubic spline interpolation method, which is 71.57% less than the original surface in 180° axis. Therefore, it was concluded that the bicubic spline interpolation method meets the requirements of the wearers. These methods are also suitable for designing other types of optical components.
The weight distributions (WDs) of spherical and cylindrical power deviations with the multiple convolution processing schemes indicate that the areas of the far and near zones can be increased by changing the WD without changing the distribution of the mean sphere. When the number of the multiple convolution processing schemes changed from 0 to 15, the areas of the far and near areas increase by 35.7% and 76.5%, respectively, and the maximum peripheral astigmatism increased from 0.75 to 1.5 ADD. The increasing maximum peripheral astigmatism will lengthen the period for the wearer to wear the PALs, and increase discomfort.
Spectacle lens are used to compensate refractive errors of the eyes. Therefore, the properties of human eyes were taken into consideration in our research. We not only designed and optimized the lens with the required optical performance in ZEMAX based on the eye-lens system, but also calculated the sag of the aspherical surface according to the optimized parameters. The back surface of the lens was aspherical surface for the better clinical effects than other types of aspherical lens. The results data were subsequently imported into the freeform verifier software (FFV) for analysis and the optical properties of the lens were calculated. It was found that the power distribution has been improved. The thickness of aspherical lens was much thinner than the spherical lens. Therefore, our research found a balance between thickness and optical performance.
Freeform progressive addition lenses (PALs) are mainly divided into distance vision zone, near vision zone, astigmatism channel and peripheral astigmatism zone. The purpose of this study was to compare the effect of the width of the astigmatism channel by changing the near vision area of PALs on the basis of the minimal model method. The change of the near vision area was mainly achieved by changing the distribution function of the main curvature difference and the average curvature weight. Firstly, two weight distribution matrices of different near vision areas were designed, and the second-order partial differential equations of the minimized model were solved by the finite element method. The surface shape of two PALs was obtained. Secondly, the freeform verifier software (FFV) (ROTLEX, Israel) was used to simulate the shapes of the obtained surfaces, and used computer numerical control machine tools to process two groups of PALs. Finally, the Visionix VM-2500 lens measuring instrument was used to measure the PALs. The simulated and measured power and astigmatism distribution contours showed that the width of the astigmatism channel increased with the increase of the near vision area, however, the peripheral astigmatism was increased. Therefore, the near vision zone with an appropriate area can provide a reference for the optimal design of PALs.
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