Abstract: A laser marking device for marking a reference point with laser light so that accurate measurements can be made to that point. The laser marking device includes a support bar that has first and second ends and a longitudinal axis extending between the first and second ends. The first and second ends are adapted to slidably rest on the horizontal portions of an adjacent pair of T-bars of a suspended ceiling. An illuminating device emits a beam of light to illuminate a reference point. The illuminating device is slidably mounted to the support bar.