| 摘要 |
<p>PURPOSE:To detect correctly by forming an infrared ray permeable filter in a columnar or prismatic shape to extend from an opening portion in an upper section of a cap to above a lack body and, coating an outer periphery of said filter with a film reflecting infrared rays. CONSTITUTION:An infrared ray permeable filter 5a in a columnar shape which is made of an infrared ray fiber or the like is held in the vicinity of an opening portion 4 of a cap 3. The filter 5a is mounted such that the bottom portion thereof is very close to a black body 21. Moreover, an outer peripheral surface of the filter is covered with a film 55 made of Au etc. having a high reflectivity. An infrared ray (A) incident from the upper surface of the filter 5a is completely absorbed by the black body 21, without leaking outside from the periphery thereof. Since the space between the filter 5a and black body 21 is narrow, an inner wall of the cap hardly invades within the viewfield of the black body 21. Thus, correct detection can be ensured.</p> |
