A 6-axis laser measurement system includes a novel 5-D measurement apparatus and a precision laser roll detector. The 5-D system measures pitch, yaw, X, Y, and Z displacements with a single setup of a laser head and detection housing. The laser roll detector uses a polarizing prism, such as a Glan-Thompson prism, and at least two photodetectors. A linearly polarized laser beam enters the prism, and the beam is split into two polarized components, the intensities of which vary with roll orientation of the detector relative to the polarized laser beam. The outputs of the two photodetectors are connected to the positive and negative inputs, respectively, of a high gain differential amplifier which provides a roll output.