HORIZONTAL SENSOR AND LASER MARKER

摘要

A horizontal sensor (10) includes a light emitting diode (1) as a light source, a water level (2) filled with liquid (2w) so that an air bubble(21) remains, a light reception unit (3) having four light reception elements (31-34), a light guide unit (4a) for guiding the light from the light emitting diode (1), and a planar light emitting unit (4b) for performing planer light emission. The light from the light guide unit (4a) is applied as a diffusion light to the water level (2) by the planar light emitting unit (4b). The light quantity distribution of the projected light of the air bubble (21) on the light reception unit (3) has the minimum point in the vicinity of the center axis of the air bubble (21) and monotonously increases as apart from the center axis of the air bubble (21) in the range substantially identical to the radius of the air bubble (21). Thus, it is possible to make the size of the light reception plane of the light reception unit (3) smaller than the air bubble shadow of the diameter of the air bubble (21), which reduces the horizontal sensor and increases its accuracy.