Abstract: An idea of imaging in near-infrared spectrum is proposed,and two kinds of composite narrowband filter system with different imaging mechanism are designed.Images of copper weld pool in tungsten inert-gas (TIG) and pulsed TIG (PTIG) welding are obtained from the front side of work pieces using normal charge coupled device sensor,and results of imaging with different observing window are discussed.Then,comparatively better imaging windows are found,and comparatively clear images of copper weld pool are obtained.From the experiment,it can be found that it is easy to obtain clear image in near-infrared spectrum in TIG welding and images obtained in the base of PTIG welding are clearer than that of TIG welding.Finally,the features of copper weld pool and control of depth are analyzed and researched.