| 摘要 |
PURPOSE:To vary a focal position by varying an area for obtaining heat in a medium or a part for giving heat. CONSTITUTION:In case of a voltage is applied to only one heating resistor 4c, as for a refractive index distribution in a heat effect medium 2, a sudden variation of a refractive index is generated in the vicinity of the heating resistor, and a luminous flux which is made incident on its part is emitted as if the wave front has been converted by a lens having a focus F1 in the vicinity of a boundary surface of the heat effect medium 2 and an insulating layer 3. Subsequently, when the voltage is applied to the adjacent heating resistor 4c and 4d, the refractive index distribution in the heat effect medium shows a slower variation of the refractive index than the case of figure A, in the vicinity of its center, by setting suitably a thickness of the insulating layer 3. In this case, a focus F2 of the refractive index distribution concerned is formed in a position separated from the heating resistor, comparing with F1, and accordingly, a focal distance becomes longer than that of the figure A. |
