Patent ID: 8098371

Claim:
An apparatus for measuring a residual stress of an optical fiber, comprising: a light generation unit that generates light; a lens unit including a rotating optical diffuser configured to suppress spatial coherence of the light emitted from the light generation unit, a plano-convex lens configured to convert light penetrating the optical diffuser into collimated light, and an iris configured to adjust a quantity of the light penetrating the plano-convex lens; a polarization unit including a fixed polarizer configured to divide the collimated light into two perpendicularly polarized light beams; a liquid crystal variable phase retarder configured to control the phase retardation of the polarized light beams by means of the electrical signal; a λ/4 wave plate into which the light penetrating the liquid crystal variable phase retarder is input; a measurement unit configured to allow the divided light beams of two polarization states to penetrate an optical fiber to be measured; and a light detection unit configured to detect the polarization states of the light beams penetrating the optical fiber.