Polycrystalline silicon hydrogen reducing furnace thermometry sight glass

The utility model provides a sight glass structure for temperature measurement of a polycrystalline silicone hydrogen reducing furnace, which comprises sight glass and a hollow drawtube running through the inner wall of the reducing furnace. The glass of the sight glasses is arranged on the hollow drawtube positioned outside the wall of the reducing furnace; a water cooling structure is arranged on the wall of the hollow drawtube where the glass of the sight glass is near. The glass of the sight glasses is single-glass structure; an air channel with two ends communicated with an air intake pipe positioned outside the drawtube and an inner channel of the drawtube is arranged on the wall of the drawtube positioned on internal surface of the glass of the sight glass. The sight glass structure of the utility model solves effectively the problem that the sight glass is polluted and silicon attachments are formed owing to water cooling, and has simple structure and ensures no pollution to the sight glass during the