| 摘要 |
PURPOSE:To facilitate introduction of light into a medium while eliminating loss thereby to provide a highly efficient element by using an optically converging medium as a medium, in which elastic waves and optical beams coact with each other. CONSTITUTION:Elastic waves of a preset wavelength are excited in an optically transparent medium 1 by means of an electro-acoustic converting element 2, to which AC signals are fed. Then, the refractive index of the medium 1 is periodically varied by the photoelasticity so that the same operations as those of diffractive grating can be obtained for an optical beam. If that medium 1 has a condensing property, the light coming from air is easily introduced into the medium 1 without the use of a converter so that the incident light 5 can be separately taken out of an emanating surface 13 highly efficiently as a transmitted light 6 and a reflected light 7. If, incidentally, the plural elements 2 are periodically placed at plural positions, where the elastic waves of a preset wavelength are aligned with the optical beam, the interacting range between inbetween can be elongated, without being influenced by the divergence due to the diffraction of the optical beam, thereby to increase the efficiency. |
