Patent ID: 7168850
Filing Date: 2007-01-30
Classification: G01N

Abstract:
1. A moisture detection device comprising: a mirror whose mirror surface is exposed to a target measurement gas; cooling means for cooling said mirror; light-projecting means for obliquely irradiating a mirror surface of the mirror with light; light-receiving means, arranged adjacent to said light-projecting means to have an optical axis substantially parallel to an optical axis of said light-projecting means and a tilt angle substantially equal to a tilt angle of said light-projecting means, for receiving scattered light of the light emitted from said light-projecting means to the mirror surface; moisture detection means for detecting moisture generated on the mirror surface of said mirror cooled by said cooling means, on the basis of the scattered light received by said light-receiving means; wherein said cooling means comprises a thermoelectric cooling element whose low-temperature-side surface is attached to a surface on an opposite side of the mirror surface of said mirror, said moisture detection means comprises a heat conductor to which a high-temperature-side surface of said thermoelectric cooling element is attached, said light-projecting means and said light-receiving means each comprise an optical fiber whose light-projecting axis and light-receiving axis are parallel to each other, said optical fibers being in a tube comprising a small-diameter fiber portion and a large-diameter fiber portion connected to said small-diameter fiber portion, and said heat conductor comprises a through hole through which said small-diameter fiber portion is inserted, a guide hole which communicates with the through hole to guide said large-diameter fiber portion, a locking portion which regulates a position of said large-diameter fiber portion in the guide hole not to make a tip of said small-diameter fiber portion but against the mirror surface of said mirror, an engaging member which is attached into the guide hole from an outside of said heat conductor to fix said large-diameter fiber portion by a tip.