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image/svg+xml Gravitational Lens Gravitational Lens Telescopes Mirror Beam-splitter +180° +2k +k +2k° +2k+2k 2k180° reinforcement cancellation
image/svg+xml Gravitational Lens Gravitational Lens Telescopes Mirror Beam-splitter +180° +2k +k +2k° +2k+2k 2k180° reinforcement cancellation