Laser interferometer for remote measurements of displacements in radiation fields

An analysis is made of the methods for measuring the radiation-induced deformations of construction materials in a nuclear reactor channel with the aid of a laser interferometer. The interferometer represents the Michelson configuration with arms whose equality is ensured by a special adjustment device. Confocal cat's eye systems are used as reflectors. The laser interferometer is operated in such a way that both reflecting systems are placed in a line in the reactor channel, one being attached to the investigated sample. This ensures a considerable reduction in the errors associated with temperature. The difference between the optical paths due to the deformation caused by nuclear radiation is measured with a resettable electronic fringe counter. In this way, movements down to ~0.16 μ can be detected.