OPTICAL ELEMENT UNIT AND OPTICAL APPARATUS

The invention relates to an optical element unit and an optical apparatus. The optical element unit is insertable into and removable from an opening portion provided in an optical apparatus, and a first portion with a first inner diameter and a second portion with a second inner diameter smaller than the first inner diameter are disposed inside of the opening portion. The optical element unit hasa third portion with a first outer diameter and a fourth portion with a second outer diameter smaller than the first outer diameter, wherein the first outer diameter is greater than the second inner diameter. Therefore, when the optical element unit is inserted into the opening portion in a reverse way, the third portion contacts with the second portion so that the optical element cannot be fullyinserted into the opening portion. 本发明涉及光学元件单元和光学设备。光学元件单元能够插入设置在光学设备中的开口部分中并且能够从所述开口部分移除，具有第一内径的第一部分和具有小于第一内径的第二内径的第二部分布置在开口部分内。光学元件单元含有具有第一外径的第三部分和具有小于第一外径的第二外径的第四部分，其中，第一外径大于第二内径。因而，在光学元件单元沿相反方向插入开口部分的情况下，第三部分与第二部分接触，使得光学元件