| 摘要 |
PURPOSE:To attain error detection and to facilitate the adjustment of an optical axis on a transmission side by folding a transmitted light beam in parallel with the optical axis, leading it to an image pickup device, observing a light source image in an irradiating position and detecting a reception device and the irradiating position based on a video signal obtained in the image pickup device. CONSTITUTION:The light beams LA1 is folded in parallel and led to a TV camera 45 which observes the side of the reception device and the adjustment of the optical axis of the light beam LA1 is executed based on a picture signal obtained in the camera 45. Thus, an error in the irradiation position of the light beam LA1 with respect to the reception device is detected on the side of a transmission device 1 and the adjustment of the optical axis is considerably simplified. For folding the light beam LA1 in parallel, half mirrors 48 and 49, a corner prism 50 or the like are used, and the positions of optical spots SP1 and SP2 are detected based on a horizontal synchronizing signal and a sub-carrier signal. |
