| 摘要 |
PURPOSE:To facilitate the adjustment of the focusing of a light beam by reflecting the light beam sent from a transmitter in a collimated direction, picking up an image and adjusting the focus of the light beam based on the obtained image pickup signal. CONSTITUTION:The transmitter is provided with optical path loopback optical systems 48-50 reflecting the light beam LA1 sent from a light beam emission optical system 36 in parallel with an optical axis L of the light beam LA1, an image pickup optical system 52 leading a reflected light beam LA4 to a photodetection face of an image pickup device 45, optical spot detection circuits 60, 61, 63-65 detecting the size of a light spot SP1 based on an image pickup signal SE obtained from the image pickup device 45 and control means 42, 66-68, 70 controlling the distance between a light source 40 and a light beam radiation optical system 36. Then the sent light beam LA1 is reflected in parallel with its optical axis L and the image is picked up by the image pickup device 45. Thus, it is possible to detect the spread of the light beam LA1 and to adjust the focus by an optical space transmitter 1 only. |
