| 摘要 |
PURPOSE:To make a high reflecting surface unnecessary, and to raise the efficiency, by providing a lot of fine inclined surfaces on the surface of the luminous flux emitting side of a substrate a transparent plane plate for making a luminous flux transmit, and constituting so that an incident luminous flux to the inclined surface from the inside of the substrate is totally reflected by the inclined surface, and also is totally reflected by the plane of the emitting side. CONSTITUTION:On the surface of the emitting side of a substrate 11 of an optical splitter 10, a fine uneven structure consisting of a plane part 12 and a wedge-like notch part 13 is formed, and the notch part 13 has a surface 14 being nearly vertical to the plane part 12, and an inclined surface 15 having an inclined angle alpha. When the inclined angle of the inclined surface 15, and a refractive index of the substrate 11 are denoted as alpha and (n), respectively, the inclined angle alpha is decided as shown in the expressionI, and when width of the inclined surface is denoted as Pd, an interval Pw of each inclined surface is formed as shown in the expression II, by which a luminous flux L1 passing through the plane part 12 transmits the substrate 11 as it is, but a luminous flux L2 which has been made incident to the inclined surface 15 is totally reflected by the inclined surface 15 and the plane part 12, is emitted into the air from the end face of the substrate 11, and is made incident to an optical detector. |
