Abstract: Because of the inherent limitation of techniques using the cornea as a mirror, we developed a corneal topographer based on diffusely emitted images obtained from two orthoscopically projected grids on the cornea. The additive moire pattern on the cornea was the starting point of the accurate reconstruction of the corneal topography including limbal and apical zone. In general, moire contouring instruments have inherent limitations on their accuracy because of limitations on maximum line frequencies versus depth of field. We eliminated this problem by using discrete Fourier analysis directly on the separately measured grids. For the reconstruction of the corneal height image, we removed all disturbance with a combination of fluorescence-, polarizing- and redundancy-techniques. With these improvements in hardware and extra digital filter techniques in software, we reconstructed the corneal height image with an axial resolution of 3 $mu@m and a lateral resolution of approximately 40 $MUL 30 $mu@m in a 21.5 $MUL 14.5 $MUL 4 mm$+3$/ measuring area. Starting from this 3D topographic cast, other corneal parameters like optical axis, radius of curvature and corneal astigmatism could be calculated. !6
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机译：摘要：由于使用角膜作为镜子的技术的固有局限性，我们基于从角膜上两个正交投影的网格获得的散射图像开发了角膜地形图仪。角膜上的附加莫尔图案是精确重建包括角膜缘和根尖区的角膜地形图的起点。通常，由于最大线频率对景深的限制，云纹轮廓仪在精度上有固有的局限性。通过直接在单独测量的网格上使用离散傅里叶分析，我们消除了这个问题。为了重建角膜高度图像，我们结合了荧光技术，偏振技术和冗余技术消除了所有干扰。通过这些硬件改进和软件中的额外数字滤波技术，我们重建了角膜高度图像，其轴向分辨率为3 $ mu @ m，横向分辨率约为40 $ MUL 30 $ mu @ m在21.5 $ MUL 14.5 $ MUL 4 mm $ + 3 $ /测量面积。从此3D地形图开始，可以计算其他角膜参数，例如光轴，曲率半径和角膜散光。 ！6
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