Abstract: A mirror unit 2 includes a mirror device 20 including a base 21 and a movable mirror 22, an optical function member 13, and a fixed mirror 16 that is disposed on a side opposite to the mirror device 20 with respect to the optical function member 13. The mirror device 20 is provided with a light passage portion 24 that constitutes a first portion of an optical path between the beam splitter unit 3 and the fixed mirror 16. The optical function member 13 is provided with a light transmitting portion 14 that constitutes a second portion of the optical path between the beam splitter unit 3 and the fixed mirror 16. A second surface 21b of the base 21 and a third surface 13a of the optical function member 13 are joined to each other.

Abstract: In a management system for a water-barrier sheet having a double layer structure with an upper sheet and a lower sheet, the interior space of the water-barrier sheet is hermetically sealed and divided into a plurality of enclosed divisions. A vacuum source introduces vacuum into each enclosed division. Pressure sensors monitor the vacuum condition in the inside of the respective enclosed divisions and a faulty division among them is identified by variation of the vacuum pressure when failure is caused. In response to detection and identification of the faulty division, a repair operation is performed. In case that penetration of water into the ground is not detected, temporary treatment for preventing the water penetration may be made by introducing pressurized air into the faulty division. For permanent repair of the division, water stop material is injected into the faulty division.

Abstract: A waste disposing ground or facility includes a space in the form of a cavity for receiving waste therein. A planar structure covers the entire overall upper opening of the cavity. The planar structure is constructed in advance of starting disposal of waste into the cavity. Arranged on the lower surface of the planar structure is a system for spraying water on the waste. Disposed at the bottom of the cavity is a system for discharging air. Since air can be discharged from the bottom of the cavity that is closed by the planar structure, the atmosphere surrounding the waste in the cavity can be changed from an anaerobic state to an aerobic state. Since water is supplied on the waste, decomposition of organic substances which decompose under aerobic conditions can be promoted. If air is not discharged from the air discharging system, the waste is placed in an anaerobic condition, and decomposition of the organic substances which decompose under such conditions can be promoted.