LONG COHERENCE LENGTH INTERFEROMETER

An interferometer has been developed which is capable of measuring the envelope of the coherence function of lasers whose mode lifetimes exc eed 300 ns, corresponding to lengths over 100 m. The precision of this interferometer is determined to be 6.0%. The interferometer utilizes optical fibers for the purpose of optical delay. The minimum resolvabl e bandwidth of the interferometer is 64 kHz. This interferometer is ca pable of measuring not only the coherence function of a single laser, but also the mutual coherence function of coupled lasers. Its resoluti on is limited only by the total length of the interferometer and the l osses in the optical fiber.