| 摘要 |
PURPOSE:To easily porduce a thin film optical element of high accuracy by forming a preset waveguide film on a glass substrate and by heating a preset portion therof thereby to reduce the refractive index thereof. CONSTITUTION:A waveguide film 11, which is made of oxide glass composed mainly of SiO2, Ta2O5 or the like, is formed by evaporation with a thcikness larger than a cut-off film thickness for a waveguide light upon the smooth surface of a glass substrate of Vycor glass. The laser beam 15 from a laser oscillator 14 of CO2 is deflected by a mirror 16 and changed into a laser beam 13 by means of a lens 17 of Ge, which is transparent for the light 15 and which has an excellent heat- resistivity, so that it is projected upon the film 11. The substrate 1 is either moved in the direction of x or y or turned in the direction theta, and the projected portion of the film 11 by the beam 13 so that a preset portion 12 is heated with the energy of the beam 13 in a desired shape. Incidentally, when a shutter 18 is turned into and out of the optical path of the light 15 thereby to stop the projection of the beam 13, the light 15 is shielded. |
