A portable articulated arm coordinate measuring machine (AACMM) is provided. The AACMM includes a manually positionable articulated arm having opposed first and second ends. The arm includes a plurality of connected arm segments, each of the arm segments including at least one position transducer for producing a position signal. A measurement device is attached to a first end of the AACMM. An electronic circuit is provided for receiving the position signals from the transducers and for providing data corresponding to a position of the measurement device. A light source is coupled to the arm and disposed to emit light adjacent the measurement device.