| 摘要 |
PURPOSE:To obtain a desired vari-focal effect, by arranging numerous mode- index lenses in series so that the refractive indexes and changes in refractive indexes of individual lenses can be superimposed. CONSTITUTION:A thin-film optical waveguide layer 2 made of LiNbO3 is formed on an LiTaO3-base plate 1 by CVD, sputtering method, etc., and, furthermore, mode index lenses 4 are formed on the base plate 1 by thermally diffusing Ti. Then a pair of positive and negative electrodes 31 and 32 are respectively formed on both sides of the lenses 4 on the base plate 1 by utilizing a photolithography technique or deposition. Optical beams propagated through the optical waveguide 2 are respectively refracted by the 50 pieces of lenses and condensed. When the impressing voltage is changed, the refractive index varies and, when the impressing voltage is made higher, the focal point moves from Point A to Point B. Such vari-focal thin-film lens can be applied to optical integrated pickups for optical disk, etc., for correcting the focal error to disk surfaces. |
