Lithium Fluoride (LiF) is an excellent VUV transmitter and also transmits in the visible and infrared spectrums between 0.15-6µm. Transmission between these ranges is over 90%. Lithium Fluoride material is relatively soft with a hardness of about HK105 and, while largely insoluble in water, does degrade by atmospheric moisture at 400°C and softens at 600°C. A protective coating is recommended. LiF is dissolved in water, therefore suitable coatings must be applied to prevent the prism from being damaged in, for example, a spectrograph unit. The material can be used as windows with a small reflection loss and transparency region of 0.11 to 6µm. The use of 60° to 72° apex angle prisms are suitable for use in spectroscopy. A problem occurs with long exposure to UV light. This leads to devitrification. The refractive index varies from 1.4391 at 0.2µm, to 1.3918 at 0.6µm, and to 1.2975 at 6µm. The manufacture of optical components must be undertaken with extreme care as LiF cleaves very easily. Steep radii are known for causing surface tearing and thus damage to the component.
Applications commonly include UV transmission windows and analysis crystals in X-Ray monochromators, as well as a variety of lenses and prisms for use in VUV, UV, Vis and IR spectrums. Windows and prisms are used in spectrographs for various wavlength regions, and especially in the VUV.
Knight Optical supply a range of quality Lithium Fluoride optical components including Lithium Fluoride windows, Lithium Fluoride lenses, Lithium Fluoride prisms, and Lithium Fluoride blanks either from stock or custom made to your specification for a range of applications. Every component is individually tested by our highly skilled technicians in our state of the art metrology lab to ensure all components meet our high quality standards.
Contact our multilingual technical sales team and discover how Knight Optical’s high quality Lithium Fluoride optical components and service can improve your instrumentation and supply chain experience.
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