| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve a modulation sensitivity by inclining the polarization direction of an analyzer by approximately half an optical angle in a direction where a polarization surface rotates due to the optical rotation property of a crystal for the crystal axis that orthogonally crosses the advance direction of light in an electrical optical crystal. SOLUTION: A photoelectric sensor has a collimater 1, a polarizer 2, a 1/4- wavelength plate 3, a Pockels element 4, an analyzer 5, and a collimater 6 in a casing 7 in the order of light incidence. A natural optical activity crystal such as Bi12 GeO20 is used for the Pockels element 4, and the polarization direction of the analyzer 5 is inclined by approximately half an optical angle in the same direction as the direction where a polarization surface rotates due to the optical activity of the crystal for the advance direction of light. For example, in the case of Bi12 GeO20 crystal that is approximately 3mm thick, the analyzer 5 is inclined by approximately 15 deg. to the right since the optical rotation angle is approximately +30 deg.. In this manner, by determining the position relationship between the Pockels element 4 and the analyzer 5 depending on the optical rotation angle of the Pockels element 4, a modulation sensitivity can be maximized.</p> |
