How to choose Vision Measuring Machine surface light and contour light?

Vision Measuring Machine according to specific workpiece, contour light is generally selected. The contour light emphasize the depth of space, it can be used to measure through hole and workpiece contour which parts have height difference. It can provide more accuracy result in this way. If the contour light can’t reach the measurement position, using surface light will be better. Such as blind hole, surface ladder. The surface light is generally used to measure contour parameters.