| 摘要 |
<p>This invention is to provide a sighting apparatus by which a user can directly observe the inside of a furnace during operating and promptly control according to the condition inside the furnace. The sighting apparatus can completely seal up the inside of the furnace and is operable with small operation costs. The sighting apparatus includes a housing having a double casing structure keeping a space between the cases into vacuum condition and a sighting hole at a front end thereof and being sealably positioned into an opening formed on a wall of a furnace, a lens block detachably mounted inside the housing, a plurality of object lenses and ocular lenses respectively positioned in the lens block, a visible ray cut-off filter and an infrared ray transmitting filter positioned next to the last ocular lens in the lens block, a screen lens mounted at an inlet portion of the lens block, and a cooling means for cooling the lens block with the compressed air. The sighting apparatus has a simple structure, provides clean image of the inside of the furace, and is easy in maintenance and repair.</p> |
