CaF2 (Calcium Fluoride) Optics and Crystals

Shalom EO provide CaF2 crystals of the following grades:

Calcium Fluoride (CaF2) Crystal, cubic, CaF2-type crystal structure, is a vital optical material renowned for its exceptional properties, making it a popular option for deep ultraviolet (DUV) applications, which is defined as 193-248nm. CaF2 are often used to manufacture optics for 248nm (KrF) excimer lasers and 193nm (ArF) excimer lasers. With its wide transmission range spanning from the VUV spectrum (below 150 nm) through the visible to the infrared (~8 μm), in combination with other advantages like low UV absorption, low-stress birefringence, stable thermal and mechanical properties, calcium fluoride crystals offer unmatched optical excellence for high-precision optics operating at short wave UV wavelengths. 

With a low chromatic dispersion (Abbe number Vd=95.23), calcium fluoride crystal is an indispensable optical crystal material for manufacturing apochromatic lenses, which are used for the correction of chromatic abberation and reduced dispersion. Calcium fluoride crystals also have negative dn/dT (temperature coefficient of refractive index), therefore CaF2 optics can be combined with materials with positive dn/dT, such as fused silica, to realize thermally stable design.

Hangzhou Shalom EO specializes in offering custom DUV/VUV optics and DUV/VUV transparent crystals. This page specifies our CaF2 crystals and CaF2 optics optimized for DUV (Deep Ultraviolet), the CaF2 crystals can also be used in an extensive spectral range from UV, VIS, to IR. With our high-purification crystal manufacturing process, Shalom EO’s CaF2 crystals feature exceptional broadband transmittance, high laser damage, and UV exposure resistance, minimized stress birefringence, excellent UV transmittance, and outstanding refractive index uniformity. Our CaF2 crystals and CaF2 optics find widespread usage, working as astronomical lenses and windows, high-definition television (HDTV) zoom lenses, microscopes, infrared camera windows, IR spectrometer windows and beamsplitters, and excimer lasers/solid-state lasers/gas lasers optics, etc. CaF2 for scintillation material for X-ray and gamma-ray detection is also available in Shalom EO.

We can provide custom calcium fluoride crystals (crystal ingots, blanks, coated or polished) of 5 different grades, the 5 different grades corresponding to application wavelength ranges from deep UV to IR. We can offer CaF2 crystals with a maximum diameter of >300mm, up to 500mm, standard (111) and (001) orientation, while other custom orientations can be tailored upon request. The CaF2 crystals are grown using the Bridgman-Stockbarger method. The transmission wavelength range is 0.13μm-8μm. The transmission rate within the calcium fluoride crystal can reach >99.8%/cm@248nm and >99.6%@193nm. Our calcium fluoride crystals also exhibit low stress ranging from 1-10nm/cm, for example, the stress for a dia310mm, height 75mm bulk crystal is 1.5nm.

We also produce CaF2 optics using advanced coating design combined with high-quality optical substrates, catering to stringent performance requirements in various application realms, including photolithography applications, ultraviolet laser applications, aerospace large aperture CaF2, and high precision CaF2 lenses. High precision is ensured with our processing capabilities like surface quality up to 10/5 S/D, and wavefront distortion up to λ/10. Coatings like AR coatings or high-reflection (HR) coatings can be deposited.

Beside the bulk CaF2 crystals, Shalom EO also supplies custom CaF2 optical components, comprising: 

• CaF2 Optical Windows: Optical windows are transparent optical components that allow light to pass with minimum distortion and loss while protecting the core optical element. Shalom EO provides a series of CaF2 windows, including flat windows, square windows, stepped windows, and more. The coatings of the windows can be selected, and caf2 windows of special shapes such as windows with drilled holes, and wedge windows are available. The caf2 windows operate well in UV, VIS, and IR wavelength ranges. Surface quality of 10/5 S/D, surface flatness of λ/10, and parallelism <10" can be achieved.
• CaF2 Lenses: Optical lenses are transmissive optical components with special surface profiles that converge or diverge light. Shalom EO supplies plano-convex/concave, double convex/concave, meniscus CaF2 lenses, etc. Optical non-homogeneity of <2ppm, and stress of <5ppm can obtained. CaF2 lenses are excellent for laser focusing of various deep UV lasers (e.g. excimer lasers), and to be used as focusing lenses of ultraviolet photolithography to obtain high resolution.
• CaF2 Prisms: right angle prisms, equilateral prisms, Dove prisms, penta prisms, roof prisms. The CaF2 prisms are great for beam steering of excimer lasers, solid-state lasers, and gas lasers.
• CaF2 Beam Splitter: Beamsplitters split light into two components according to polarization or splitting ratio.
• Various custom-shaped CaF2 optics: cylindrical lenses, rod lenses, micro lenses, waveguides, etc.

Typical Applications of CaF2 Optics and Crystals:

• Optical Windows and Lenses: Calcium fluoride crystals can be used as transmissive optics in the UV, VIS, and IR regions, such as optical windows and lenses.
• UV Laser Components: CaF2 crystals can be used as optical elements for DUV lasers like excimer, solid-state, and gas lasers. The UV laser processing technique is adopted as one of the most common techniques for patterning semiconductors.
• Scintillators: CaF2 is also a scintillator material for detecting X-radiation and gamma radiation for medical imaging.
• Astronomical Applications: telescope lenses and windows.
• Others: Semiconductor testing, microscope, and other deep ultraviolet applications.

Tranmsmission Curve of Shalom EO’s CaF2 Crystals:

Wavelength Curve of Shalom EO’s CaF2 Crystals: