A position measurement system is configured to measure its position in one or more degrees of freedom with respect to a beam of light while addressing errors caused by atmospheric distortions. Atmospheric distortions can be measured using a wavefront sensor. Data from such a sensor can be used in combination with a beam position sensing device, such that wavefront data can determine if beam position device data should be discarded or can be used to correct the beam position device mathematically. Alternately, the wavefront sensor data can be used to control an adaptive optic that has the ability to receive a distorted beam and then transmit an undistorted beam to the beam position sensing device, eliminating the need to mathematically correct the data from the beam position sensing device. Finally, the wavefront sensor itself can be used to both measure wavefront distortions as well as determine beam position.