| 摘要 |
PURPOSE:To condense light to small area (of optical fiber, etc.) efficiently without leaking light out, by decreasing the refractive index of a condenser, which is sectioned circularly and decreases in diameter lengthwise, from the center of the area to the circumference. CONSTITUTION:Light is emitted from the largest-diameter part 2L of a circularly sectioned condenser 2 having the distribution that the refractive index IR-1 of the section S-1 decreases from its center part to the circumferential part. Light approaching the flank of the condenser 2 increases light in velocity rapidly and is bent to the center axis of the condenser 2 at any time. Therefore, light traveling from the largest-diameter part 2L to the smallest-diameter part 2S, while waving as shown by the solid line, reaches the smallest-diameter part 2S without leaking out. AY this time, when the refractive index decreases to the smallest-diameter part even lengthwise, the leakage of light is further decreased. |
