optical crown

1. A lens made of optical crown glass.
   用冕光学玻璃制成的透镜。
2. This thesis represents the application of an optical method to obtain the 3-D parameters of teeth surfaces for the purpose of design veneer and artificial crown by computer-aided design.
   本论文尝试应用一种新的牙冠三维光学测量方法，以求精确测量牙冠外形，为义齿CAD-CAM系统增添新的测量手段，并在此基础上尝试贴面与全冠的计算机辅助设计研究。
3. Conclusion: This phenomenon is of reversible and inevitable optical nature because of the light transmission of the free gingiva and the existence of metal base crown which blocks the lights from the internal tooth structure and darkens the root.
   结论：由于游离龈的光透过性及金属基底冠对牙根的阻光作用，基牙游离龈变色是一种不可避免的可逆光学现象。
4. A hybrid geometric optical and radiative transfer approach is used to parameterize the four component spectral signatures ( sunlit crown, sunlit background, shaded crown, and shaded background) in geometric optical reflectance models over discontinuous plant canopies.
   该文用几何光学与辐射传输混合模型研究不连续植被冠层的几何光学反射模型的四分量（承照树冠、承照地面、阴影树冠、阴影地面）的参数化。

noun

1. optical glass of low dispersion and low refractive index

   Synonym:    crown glassoptical crown glass