Abstract: A gas leakage detection system 1 with high detection accuracy for a remaining gas amount and a gas leakage amount of an insulation gas 28 in a container 27 forming a electrical apparatus 2 is provided.

Abstract: An optical pickup device includes a pickup base, an optical system, a light emitting element, and a heat transfer holder which transfers the heat of the light emitting element to the pickup base. The heat transfer holder includes a holder base and a holder main body overlapped to the holder base. The holder base is arranged around the light emitting element and has a first flat contact surface which comes into surface contact with an abutment surface of the pickup base, and a second spherical contact surface, which is positioned opposite to the first contact surface. The holder main body has a third spherical contact surface which comes into surface contact with the second contact surface of the holder base, and an engaging recess formed in the third contact surface and having an inner surface which contacts with the light emitting element.

Abstract: 0 In an optical pickup of the invention, the center of a laser beam incident on a dichroic prism can easily correspond to the center of an objective lens by a heat sink, which is held by a boss portion inserted into a through hole provided in an optical base and a boss plate having a plane portion in which the boss portion can be moved in the through hole in a direction orthogonal to an axis line of the boss portion.