Weld pool viewing system

In a welding system,

• the combination of,
• a welding torch means for producing a weld pool at the seam of a workpiece in response to an arc contacting the workpiece,
• first means for positioning and moving said welding torch means along a direction of travel relative to the seam,
• second means for controlling the welding parameters of said welding torch means,
• vision means for viewing the weld pool at an angle relative to the axis of said welding torch means so as to produce a weld pool image including the interface of the weld pool with the workpiece and generating signals indicative thereof, said signals being transmitted to said second means to control the quality of the weld produced at the seam of the workpiece,
• said vision means including,
• a tubular viewing port angularly disposed in advance of the direction of travel of the welding torch means and having an open end for viewing the weld pool and weld pool interface with the workpiece,
• a camera means optically coupled to the opposite end of said tubular viewing port,
• a series of optical elements positioned within said tubular viewing port to define an optical path, said elements comprising,
• a transfer lens means for forming an intermediate image of the weld pool at a position along said optical path,
• a gradient density filter means positioned coincident with the image plane of the transfer lens to effectively darken the portion of the intermediate image corresponding to the arc thereby reducing the intensity gradients across the weld pool image, and
• a camera means for viewing the weld pool image developed by said gradient density filter and transmitting weld pool image information to said second means.