Liu L
Shanghai Institute of Optics and Fine Mechanics, Academia Sinica, Peoples Republic of China.
Optom Vis Sci. 1994 Apr;71(4):265-72. doi: 10.1097/00006324-199404000-00007.
The measurement of spectacle lenses by conventional focimeters and automated focimeters assesses only a small region of the lens, and only the power and related data at that point are indicated. In this paper, two methods based on optical Fourier filtering and optical correlation are suggested for contour-mapping the deviations of a spectacle lens over its whole aperture. The fringe pattern appearing on the lens image depicts vividly the characteristics of the tested lens. All the related data are qualitatively seen at a glance and can be calculated from the fringe distribution. Furthermore, the optical processing of the fringes by defocusing is described; thus, the fringes can be continuously changed by shifting the illuminating point source or mask. The shift indicates the spherical power needed to decrease or increase the lens fringes. In addition, a fringe-reading technique is suggested by counting the number of the fringes within a reticle ring. Therefore, the sphere power, cylinder power, cylinder axis, prism power, and prism orientation can be obtained from the reading of the fringes, the shift position, or their combination with a high accuracy. The methods are suitable not only to sphere, spherocylinder, and prism lenses but also to multifocus and progressive power lenses. The suggestion provides a practical way to measure spectacle lenses over the whole aperture.
传统焦度计和自动焦度计对眼镜镜片的测量仅评估镜片的一小部分区域，且仅显示该点的屈光力及相关数据。本文提出了两种基于光学傅里叶滤波和光学相关的方法，用于对眼镜镜片整个孔径上的偏差进行轮廓映射。出现在镜片图像上的条纹图案生动地描绘了被测镜片的特征。所有相关数据一目了然，且可从条纹分布中计算得出。此外，还描述了通过散焦对条纹进行光学处理的方法；因此，通过移动照明点光源或掩模可使条纹连续变化。这种移动表示减小或增加镜片条纹所需的球镜屈光力。此外，还提出了一种通过计算标线环内条纹数量的条纹读取技术。因此，通过读取条纹、移动位置或它们的组合，能够高精度地获得球镜屈光力、柱镜屈光力、柱镜轴位、棱镜屈光力和棱镜方向。这些方法不仅适用于球面、球柱面和棱镜镜片，也适用于多焦点和渐进多焦点镜片。该提议为在整个孔径上测量眼镜镜片提供了一种实用方法。
