摘要 |
A thin lens consists of a first optical element which comprises a first refracting surface, wherein incoming light passes through the first refracting surface on a first optical axis. A reflecting surface changes a direction of the incoming light from the first optical axis to a second optical axis. Incoming light on the second optical axis passes through a second refracting surface. A second optical element comprises a first refracting surface, wherein incoming light passes through the first refracting surface on the second optical axis. A reflecting surface changes a direction of the incoming light from the second optical axis to a third optical axis. Incoming light on the third optical axis passes through a second refracting surface. The third optical axis is approximately parallel to, and in opposite direction from, the first optical axis.
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