| 摘要 |
The variable spectroscopic element includes a pair of optical substrates 21-22, four sensors 31-34, four piezoelectric elements 41-44, and a control section. The sensors 31, 33 are arranged to form symmetry with respect to the center axis, which links gravity centers of mutually facing surfaces of the optical substrates 21-22, and so are the sensors 32, 34. The control section calculates, from signals of the sensors 31-34, a distance x between the gravity centers of the mutually facing surfaces, and angles &thetas;, &phgr; each of which is formed by a plane perpendicular to the center axis and the facing surface of the movable substrate 22, to drive the piezoelectric elements 41-44 on the basis of the distance x, the angles &thetas;, &phgr;, and to carry out feedback control and feed forward control with respect to at least one of the distance x, the angle &thetas;, and the angle &phgr;. |
