Morphological and optical properties of the corneal lens and retinal structure in the posterior large stemma of the tiger beetle larva
Morphological and optical properties of the corneal lens and retinal structure in the posterior large stemma of the tiger beetle larva
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DOI：
10.1016/j.visres.2007.02.023
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发表时间：
2007-06
期刊：
影响因子：
1.8
通讯作者：
Y. Toh;J. Okamura
中科院分区：
文献类型：
--
作者：
Y. Toh;J. Okamura
本文观察了虎甲虫幼虫后大茎的角膜透镜和视网膜的形态学和光学特征。角膜透镜后缘下55 ± 6 μ m处有一杯状视网膜，直径479 ± 20 μ m，厚度391 ± 18 μ m（n = 41）。通过离体角膜透镜的光路表明，无限远的物体聚焦在视网膜的远侧边缘。几何光学给出的角膜透镜后焦距值为334 ± 15 μ m（n = 55）。如果认为透镜结构均匀，则角膜透镜的折射率估计为约1.8。据推测，透镜的内部结构，包括同心薄片，有助于如此高的折射率，因为这比昆虫角质层的折射率高。还检查了视网膜结构以及在不同焦点水平下图像如何模糊。获得的数据进行了讨论，参考不同的视觉行为的幼虫的角膜透镜和视网膜结构的光学。
The morphological and optical features of the corneal lens and retina have been examined in the posterior large stemma of the larva of the tiger beetle (Cicindela chinensis). A cup-shaped retina was positioned 55±6μm beneath the posterior margin of the corneal lens, which was 479±20μm in diameter and 391±18μm in thickness (n=41). A light path through an isolated corneal lens showed that the object at infinite distance was focused on the distal margin of the retina. Geometrical optics gave a value of 334±15μm (n=55) for the posterior focal length of the corneal lens. The refractive index of the corneal lens was estimated to be around 1.8, if the lens was considered to be homogenous in structure. The internal structure of the lens, including concentric lamellae, was presumed to contribute to such a high refractive index, because this was higher than that of insect cuticle. The retinal structure and how images were blurred at different focus levels were also examined. Data obtained for optics of the corneal lens and retinal structures are discussed with reference to the distinct visual behavior of the larva.