| 摘要 |
An indicator has two radiation sources supported in a housing and directed to two perpendicular directions to generate two light beams and to indicate a right angle. A semi-transparent mirror is engaged in the housing, the light beam generated by one radiation source has a portion transmitted through the mirror and another portion reflected by the mirror to indicate another right angle, and to indicate two opposite points far spaced from each other. A cover has three windows aligned with the light beams for allowing the light beams to be transmitted out of said cover.
|
