| 摘要 |
PURPOSE:To know correctly the scanning position of projecting beam of a semiconductor laser by obtaining plural referring spot light beams or referring slit light beams. CONSTITUTION:The output light of a semiconductor laser 2 is shaped by a collimator lens 3 and a slit plate 4, converged by the first converging means 5, comes to a projecting beam, further, scanned by a scanning means 6 and irradiated on a bar code 7. The projecting beam goes straight ahead an overlapping means 12. The visible light from a visible light source 10 is converged by a cylindrical lens (third converging means) 11, overlapped to the projecting beam by a dichroic mirror (overlapping means) 12 and the visible light also irradiates the part in which the projecting beam irradiates on the bar code 7. The reflecting light reflected by the bar code 7 is converged by the second converging means 8 and photodetected by a photo sensor 9.
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