| 摘要 |
PURPOSE:To obtain a relatively large temp. gradient in the part on an incident side of a light beam and to obtain a relatively large deflection angle by forming an optical material so as to have the thickness thinner on the incident side than on the exit side of the light beam. CONSTITUTION:A crystal 11 of lithium niobate is formed to a wedge shape of which the thickness is larger the nearer the rear end. The front end of the crystal 1 is formed to the thickness slightly larger than the diameter of the light beam A and the rear end thereof is formed to such as thickness at which the light beam can arrive at the rear end face without arriving at the top and bottom surfaces of the crystal 11. A temp. gradient is generated in the vertical direction in the crystal 11 when electric current is passed to both Peltier elements 2 to heat the top surface of the crystal 1 by, for example, the upper element 2 and to cool the bottom surface of the crystal 11 by the lower element 2. Since the thickness of the front part is thin, the relatively large temp. gradient, i.e., refractive indes gradient, is generated in the front part. The light beam heads for the rear end face while the beam is deflected gradually upward. |
