A device for determining a penetration depth in a drilled hole which is drilled into a workpiece (W) from a workpiece surface (WO) with a drill of a drilling machine. The device contains at least one light source for projecting a light field is provided onto a workpiece (W) to be processed by the drilling machine. The light source is positioned with respect to the drilling machine in such a way that a center axis (L) of the light source runs at an angle (a) with respect to a central axis (L) of the drilling machine, and at least a first blocking element for partially covering the light source is provided, said blocking element forming a reference on the light field.
