| 摘要 |
<p>PROBLEM TO BE SOLVED: To produce linear output and to attain reception with high sensitivity by setting the total area of an radiating outlet window and a photodetecting inlet window at a specific rate against a membrane area and also including the concave multi-dimensional function curves more than a specific dimension in a vertical section shape of an electromagnetic wave light guiding part. SOLUTION: The total area of an outlet window 8 and an inlet window 7 is set at 5% or less of a membrane area. The wide spaces are secured at the places near a membrane 5 and both windows 8 and 7 to reduce the harmful effects of the negative pressure against the vibrations of the membrane 5 if a light guiding part 9 includes the concave curve parts of 1.2 dimensions or more. As the outside of the part 9 consists of a continuous curve, the gas existing near the part 9 smoothly moves and functions to improve the linearity of the signal output. When the angle is set asαbetween the curve tangent and a substrate, the light emitted vertically from a light emitting element 1 is reflected by the curve and reaches the window 8 at an incident angle of (180-2d). Thus, the light is emitted to the outside through the window 8 as long as the said incident angle is set smaller than the critical angle of a light shielding material.</p> |
