Since 1992, LTS has been producing mil-spec compliant fluoride materials using the Direct Fluorination Method (DFM). LTS produces the highest quality fluorides available in the industry: Our novel DFM process allows for the production of extremely pure compounds with superior deposition properties.
Fluoride compounds produced via hydrofluoric acid (HF) reactions have impurities in the precipitated compound which are not easy to purify out.
The Direct Fluoridation Method (DFM) is a specialized process defined by a high temperature plasma phase reaction of two or three components to increase the purity, viscosity, and consistency of the material. Then, secondary melting in fluorine gas atmosphere compensates for fluorine stoichiometry deficiencies.
The process is costly, cumbersome, and occasionally non-deployable in the cases of scandium fluoride (ScF3), aluminum fluoride (AlF3), cryolite (Na3AlF6), and a few other Rare Earth solutions of fluorides. LTS employs the DFM process in its production of ultra-high purity fluorides such as LaF3, GdF3, NdF3, LiScF4, CaF2, and MgF2 production for DUV-NIR applications, as well as YbF3, YF3, BaF2, CeF3, and our thorium fluoride (ThF4)replacement chemicals, solid solutions of YBC fluorides for IR applications.
The process effectively removes contaminants as well as trapped gases. The result is a significantly purer material that undergoes faster, cleaner deposition and ultimately provides a better optical coating.
Specialized YBC Materials
YBC DFM is a highly preferred category of low-index materials transparent from the NIR to IR regions of the spectrum. YBC DFM materials are recommended for multilayer coatings in AR applications in the 2,000-12,000 nm region, including AR, bandpass, and dichroic filters. They are also suitable for laser coating applications.
- YBC-375: The stoichiometry of this material has been optimized for easy deposition onto Ge and ZnSe substrates, making YBC-375 highly suitable for All IR and CO2 laser component applications.
- YBC-905: The stoichiometry of this material has been optimized to form a superior durable coating onto the substrates used in the CO2 laser applications; however, a high quality deposition is more difficult to achieve than with YBC-375. In addition, YBC-905 cannot be used in high humidity environments or applications around the 3.8 and 5.6 micron range as it has absorption bands in that region of the spectrum.
- YBC-907: The stoichiometry of this material has been optimized for extremely low absorption in NIR/IR applications. It is mildly toxic but outperforms radioactive thorium fluoride, making YBC-907 the superior material for use in CO2 laser component films.
Non-radioactive Thorium Fluoride IR-coating replacement
- Lanthanum Fluoride LaF3
- Neodymium Fluoride NdF3
- Gadolinium Fluoride GdF3
- Aluminum Fluoride AlF3
- Erbium Fluoride ErF3
- Cryolite Na3AlF6
Mid-index Fluoride solutions:
- Scandium Fluoride ScF3
- Lithium Fluoride LiF
- Yttrium Fluoride YF3
- Ytterbium Fluoride YbF3
- Dysprosium Fluoride DyF3
- Cerium Fluoride CeF3
DFM grade fluoride materials for high quality and fast deposition in UV, mid-range, and IR thin film coatings.
Hafnium Oxide HfO2
Usable Spectrum: 224 nm - 8 µm
Index: 2.0 @ 500 nm
Scandium Oxide Sc2O3
Usable Spectrum: 250 nm - 8 µm
Index: 1.8 @ 500 nm
Zirconium Oxide ZrO2
Usable Spectrum: 230 nm - 7 µm
Index: 2.0 @ 500 nm
Scandium oxide is a high laser damage threshold optical coating material for use in UV laser applications at 337 nm and 248 nm. It has a LDT of >6 J/cm2 as well a moderately high index of refraction of ~1.8 at 550 nm. It is durable and has good adhesion promotion.
These properties make Sc2O3 a valuable antireflection / high-reflection and multilayer coatings material for ultraviolet applications as well as visible and infrared.
Unfortunately, due to its ores’ rarity, scandium oxide is also very expensive.
For this reason, LTS has developed scandates with similar or better optical properties that are cheaper and more accessible to the medium budget user. These are based on compounding scandium oxide with other rare earth oxides to form ternary compounds with less than half the scandium content but equivalent optical properties, including higher density and refractive index.
Rare Earth Scandates:
- Gadolinium Scandate GdScO3
- Yttrium Scandate YScO3
- Hafnium Scandate HfO2-Sc2O3