An optical angle of arrival measurement system uses an optical element to form at least one narrow width line on a focal plane array (FPA) which is oblique with respect to the FPA's row and column axes and which traverses at least two rows or columns along its length; forming two perpendicular narrow width lines in a cross-pattern is preferred. Interpolating the position of the lines on the FPA provides coordinates that can be used to calculate the optical angle of arrival in accordance with θx=A(x)·tan−1(x/f), and θy=B(y)·tan−1(y/f), where f is the focal length of the optical element, and A(x) and B(y) are parameters that account for optical distortion and other imperfections of the system. The resolution δθ of the angle of arrival measurement can be improved to at least δθ˜(d/n)/f, where d is the FPA pixel width and n is the length in pixels of the imaged line.