摘要 |
The invention is directed to an optical unit having elements (6, 7) which are juxtaposed without an air gap therebetween. The two elements (6, 7) are joined by wringing the same to each other. At least one element (7) is of crystalline material and has an amorphous inorganic layer (70) on the side thereof facing toward the other element (6). The invention is also directed to a method of preparing an element made of crystalline material, such as a fluoride, as well as a method for making a thin optical element of the crystalline material.
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