| 摘要 |
<P>PROBLEM TO BE SOLVED: To certainly convert linear polarized light into circular polarized light, even when a one-quater wavelength plate generates phase deviation on emission light in an optical system of an optical sensor. <P>SOLUTION: A vibration detecting optical sensor 1 comprises a light source 2, a polarized light beam splitter 3, an objective lens 4, a wavelength plate unit 5, and one light receiving element 6. The wavelength plate unit is composed of a one-quater wavelength plate 7, a vibration plate 8, and phase correcting element 9 which are integrated. The phase correcting element is made from a liquid crystal layer 13 put between transparent substrates. When phase deviation is generated in the emission light of the one-quater wavelength plate, voltage corresponding to action temperature is applied on the liquid crystal layer to change a retardation value, thereby converting the linear polarized light into the perfect circular polarized light. The light receiving element is disposed so as to make its optical axis x2 in parallel with and slightly shift from an optical axis x1 of reflection light, and an incident beam spot shape is projected at a position where its center c is slightly shifted from a center O of a light receiving surface 6a, so that detected light amount is increased and decreased according to the displacement of the vibration plate. <P>COPYRIGHT: (C)2012,JPO&INPIT |
