An optical system includes a light source, a target device, an image detector, and an autocollimator that receives a beam of electromagnetic radiation from the light source, directs the beam to the target device, and directs the beam to the image detector. The autocollimator includes a first polarizing beam splitter that directs the beam to the target device and receives the beam reflected off of the target device, a second polarizing beam splitter that receives the beam from the first polarizing beam splitter, directs the beam to a diffraction grating device, returns diffracted electromagnetic radiation from the diffraction grating device to an array of detectors, and directs the diffractive electromagnetic radiation, a camera that measures an interference pattern of diffracted electromagnetic radiation from the second polarizing beam splitter and captures an image, and a lens assembly that focuses electromagnetic radiation from the target device to the diffraction grating device.