Getting To Know LBO
GET TO KNOW LITHIUM TRIBORATE BETTER
Lithium Triborate, LiB3O5, or LBO - all the same to me, but let's be friends, just call me LBO. I am an outstanding crystal for non-linear optics, the best of my type. But why am I special, so special? It probably has something to do with the lithium.
Lithium has many uses and unique properties. It is atomic number 3, the lightest of metals and lightest solid. It will float on water or even oil, although it is very reactive with water.
Even More About Lithium Triborate
High purity lithium triborate is transparent from 160 to 2600 nanometers. The best material, such as GAMDAN produces, has very low absorption. This has been proven by two beam absorptance measurement, PCI, for Photo-thermal Common-path Interferometry.
Lithium triborate (LBO) crystals are especially suitable for various nonlinear optical applications: Frequency doubling (SHG for second harmonic generation) and frequency tripling (THG for, you guessed it, third harmonic generation) of high peak power pulsed Nd doped, Ti:Sapphire lasers and Dye lasers.
LBO is very well suited for harmonic generation of neodymium YAG or YLF lasers into the deep UV, as it has exceptional laser damage resistance. Despite lithium metal being very reactive and incompatible with water, LBO has good chemical stability and excellent moisture resistance.
Where Else is Lithium Used?
Lithium compounds find many uses. Lithium batteries are well known, for long lasting button cells in watches, cameras, and the like, to rechargeable lithium ion batteries in cell phones, laptops, even automobiles like the Tesla. The long lifetime combines with light weight to make for an excellent portable battery, far better than lead acid batteries. There are actually several chemistries of lithium batteries with various cathodes and electrolytes, that all have metallic lithium as the anode.
Lithium carbonate was an early drug used to treat bipolar disorder and depression. White lithium grease is heat and water resistant. There is probably some on your car door hinges or latches.
Lithium alloys of metals like aluminum and magnesium are an excellent combination of strength and lightness. They have applications for armor plate or aerospace uses. Lithium compounds are used as catalysts in a number of industrial processes. Lithium hydroxide can absorb carbon dioxide and generate oxygen in spacecraft or submarines. Lithium silicate densifiers (hardeners) for concrete are replacing sodium and potassium silicates.
Lithium oxide is used in some glasses and ceramics. Best known is Schott ZERODUR®, which Schott describes as "an inorganic non-porous lithium aluminum silicon oxide glass ceramic characterized by evenly distributed nano-crystals within a residual glass phase." Whew!
There are other trademarked brands of low expansion glass with similar composition; they all rely on the same properties of particular lithium crystals. They each have an amorphous (vitreous) component and a crystalline component. The vitreous phase has the typical positive coefficient of expansion. But the lithium crystalline component has a negative coefficient.
During a special annealing operation, the growth of the (shrinking) crystalline phase is closely monitored until it precisely matches and cancels the positive expansion of the remaining vitreous material. Applications include astronomical mirrors, laser gyro bodies, semiconductor manufacturing components, and temperature stable length standards or scales.
AND WHERE WOULD STAR TREK BE WITHOUT DILITHIUM CRYSTALS?!
LITHIUM IS EVERYWHERE
Lithium is also present in trace amounts in the human body. The daily requirement is not much, about 1000 μg/day for a 70-kg (154 pounds) adult (14.3 μg/kg body weight).
Lithium compounds are also key to the properties of certain optical single crystal materials. They are known for good transparency across a wide spectrum.
Lithium niobate is a well known single crystal grown by the Czolchraski method. LNB, as it is also called, has almost every "electro-" property known to man: electro optic, ferro electric, piezo electric, dielectric, plus it has acoustic optical and photorefractive and photoelastic properties as well. It is mechanically and chemically stable, although it chips or fractures somewhat readily. Lithium niobate is fabricated into wafers, chips, and relatively small blocks. The end products can be waveguides, SAW wafers (Surface Acoustic Wave), optical modulators, laser Q-switches and polarization rotators, among others. The transparency is good from 350 to 5200 nanometers.
Which brings us back to, Voila! LBO
DENNIS J. GARRITY, AUTHOR
Dennis is an engineer with over 45 years of experience in fabrication, testing, and material evaluation for high precision optics, with extensive hands-on experience. More on the author can be found here.
GAMDAN style Super Polishing and high Laser Damage Initiation Threshold coatings take the best advantage of LBO's particular properties.
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