Optical element made from fluoride single crystal, method for manufacturing optical element, method for calculating birefringence of optical element and method for determining direction of minimum birefringence of optical element

摘要: The present invention provides a method for calculating the birefringence of an optical element and selecting direction minimum in element. A material manufacturing is fluoride single crystal with value that reduced compared to conventional materials. cut from ingot obtained by growth so {111} planes are two parallel planes, after which performance improved subjecting this heat treatment. calculated converting known piezo-optical constants specified three-dimensional orthogonal coordinate system into arbitrary system. amount change refractive index Δn 1 first along one axis system, 2 second perpendicular using uniaxial stress applied as seen third determined determining difference between 2.