If the referencemirror has tilt and piston errors caused by phase-shifting, the phase shifts of the pixels along the same interferogram are not a constant, but they are still kept on the same plane.
The interferograms are modulated by the displacements of the virtual point sources of the reference beams due to motion of the small mirror.
这些干涉图被由小平面反射镜运动造成的参考光虚点光源的位移所调制。
3
A new method for focal length measurement is presented based on the self-reference single plate shearing interferometric technique and compensation of spherical mirror.