| 主权项 |
1. A detector, comprising:
a light emitter; at least one light receiver; and a light guiding member which includes a detection space for determining a state of a predetermined gas and is configured to guide light emitted from the light emitter to the at least one light receiver through the detection space, an internal surface of the detection space of the light guiding member including at least one reflective surface causing reflection of light emitted from the light emitter, the at least one reflective surface being a concave ellipsoidal surface having a long axis defined by a straight line determined by the light emitter and the at least one light receiver, and the at least one reflective surface having a first focal point at a position of the light emitter and a second focal point on an opposite side of the at least one light receiver from the first focal point. |
