Terahertz imaging

An imaging system with the ability to produce clear images of deposits inside operating high temperature process equipment such as kraft recovery boilers and power utility boilers uses a terahertz/mm-wave imaging system. This system allows direct inspection capability and the ability to directly measure deposit thickness on tubes and other interior surfaces at all locations within the boiler and precipitator. Terahertz and mm-wave imaging systems employ active imaging in which a beam of terahertz or mm-wave radiation generated within the imaging system is used to illuminate a region of the scene under investigation. The reflected radiation is collected by a lens or mirror system and focused onto a detector that converts the collected radiation into an electrical signal. Both the illuminating beam and the receiving optics are scanned across the scene in a raster fashion to produce a time-varying signal that is converted into an image of the scene.