Illuminator for inspecting substantially flat surfaces

Illuminator apparatus for illuminating a workpiece during visual testing thereof, the illuminator comprising: a source of illumination that illuminates a portion of the workpiece with on-axis illumination centered at a first angular direction and having a first intensity and with off-axis illumination having a second intensity; and an optical viewing system, that views said portion of the workpiece and accepts light reflected from the workpiece over a range of angular directions, centered at a second angular direction, said range of angular directions defining said on-axis illumination, wherein said first intensity and second intensity art separately adjustable and wherein the first angular direction is different from the second angular direction.