| 摘要 |
A material containing optical device utilizing a housing having a bottom, and a side. The side sealingly engages the bottom and extends outwardly from the same to form an open chamber. The open chamber terminates in a mouth with an entrance. A cap extends transversely relative to the mouth of the chamber to close the entrance. A first optical elements located in the bottom of the housing and permits light to travel into the chamber. A second optical element is located in a removable cap. The first and second optical elements are lined to adjust the visual angle of an object viewed through the chamber.
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