| 摘要 |
<p>PURPOSE: To make possible appropriate selection of a case when a noise component being consequent on a stress strain inside a body to be inspected is made to appear in interference fringes and a case when it is not made to appear therein, by making aλ/4 plate so that it can be put in and taken out of an optical path of a polarized light. CONSTITUTION: A laser light 2 from a laser light source 1 is made a linearly polarized light having a plane of polarization in a prescribed direction by a polarizing filter 3. In the case when the laser light 2 is made a circularly polarized light, subsequently, aλ/4 plate 4 is inserted into an optical path by operating it, and when it is made the linearly polarized light, on the other hand, the plate 4 is withdrawn outside the optical path. In the case when the laser light 2 is the linearly polarized light, moreover, aλ/2 plate 5 is inserted into the optical path by an operating mechanism of the plate 5, and when it is the circularly polarized light, on the other hand, the plate 5 is withdrawn outside the optical path. In the case when the laser light 2 is the linearly polarized light, regulation is conducted so that interference fringes wherein no line of division exists be obtained, by changing an angle of rotation of the plane of polarization by rotating the plate 5.</p> |
