Interferometer and interference method for generating stable vortex beam

The present invention relates to an interferometer and interference method for generating stable vortex beam. The interferometer includes a beam splitter, a Dove prism, a polarizing beam splitter and a phase delay apparatus. The beam splitter is used for splitting an incident light beam into a first light beam and a second light beam. The Dove prism rotates along the light axis of the first light beam, and the first light beam passes the Dove prism to form an elliptical polarized light beam. The polarizing beam splitter is used for splitting the elliptical polarized light beam into a third light beam and a fourth light beam. The phase delay apparatus includes two mirrors for reflecting the second light beam to the polarizing beam splitter to form a fifth light beam. There is a phase delay between the fifth light beam and the third light beam, and the fifth light beam interferes with the third light beam to form an output vortex beam. Whereby, the output vortex beam may be multi-vortex or vortex-array light be