| 摘要 |
PURPOSE:To adjust the quantity of the light to be outputted by movably supporting a lens for condensing along an optical axis and using a light absorbing body to form the cylindrical inside wall within the movable range of the lens for condensing. CONSTITUTION:This collimator head has the lens 14 for condensing on the light incident side on the optical axis from a light source 10 and has a lens 18 for collimating on the light exit side. The lens 14 for condensing is supported movably along the optical axis on the light exit side from the position where the light from the light source 10 expands to the size of the aperture diameter of the lens 14 for condensing. The cylindrical inside wall 20 within the movable range of the lens 14 for condensing is formed of the light absorbing body. The light from the light source 10 is, therefore, fully condensed if the lens 14 for condensing exists on the light source side 14a of the movable range W1. On the other hand, only a part of the light spread by being radiated from the light source is condensed when the lens 14 comes to the position of 14b. The light which is not condensed is thus absorbed in the cylindrical inside wall 20 of the light absorbing body. The output of the light with which an object to be measured is irradiated is increased and decreased even if the quantity of the light radiated from the light source 10 is constant. |
