Abstract: As apparatus for sensing reflected light patterns in the presence of a welding arc has an image-sensing means. Means is provided for directing one or more pulses of light of short duration at a workpiece. Each pulse has a peak intensity greater than that of the welding arc. A means is provided for blocking the light image from the sensing means except during a pulse from the light-directing means. An image sensing process includes the steps of directing light at the workpiece in one or more pulses, each of greater intensity than the welding arc. Light from the pulse reflected from the workpiece is sensed during the pulse, and sensing of light from the welding arc is blocked during the absence of a light pulse. This apparatus and process allows improved sensing of the light patterns in the presence of the welding arc and welding sparks.