| 摘要 |
PURPOSE:To emit a wave guide light as a Gaussion beam very effectively out of an optical wave guide or to make an outside light incident by setting the inclination of the height change of a diffraction grating to a specific value. CONSTITUTION:The diffraction grating of the optical wave guide element is so formed in an optical wave guide element in which a diffraction grating for emitting a wave guide light propagating inside the optical wave guide to an outside is formed on the surface of an optical wave guide so that a grating height (h) is gradually increased approximatelly linearly along the propagating direction of the wave guide light. Furthermore, the inclination (b) of the change of the grating height is set so as to satisfy the equation, where a (alpha=ah<m>:2<m) is a coefficient determining a radiant loss coefficient alpha, and L is the length of the grating in the propagating direction of the wave guide light. The light intensity distribution of a light emitting through the diffraction grating is made to be approximatelly Gaussion distribution. Therefore, it is possible to converge the light emitting from the optical wave guide to a very small spot, and to increase the accuracy of an image recording or image reading. |
