Balanced Optical Discriminator

A balanced optical discriminator for detection of angle modulation on a light beam is discussed. The device is similar, in principle, though different in form, to bridge-type microwave discriminators and optical birefringent crystal discriminators. An angle-modulated system at optical frequencies, employing a balanced discriminator, has advantages over intensity modulated systems which are familiar at radio frequencies. In addition, an angle modulated system is not as sensitive to strains, due to heating or crystal growth, in the modulating medium or to inhomogeneities in the transmission medium.