{"id":696,"date":"2026-10-18T14:54:35","date_gmt":"2026-10-18T14:54:35","guid":{"rendered":"https:\/\/glassubstrate.net\/en\/?p=696"},"modified":"2026-11-07T20:01:27","modified_gmt":"2026-11-07T20:01:27","slug":"optical-glass-materials-types-grades","status":"publish","type":"post","link":"https:\/\/glassubstrate.net\/en\/optical-glass-materials-types-grades\/","title":{"rendered":"How Many Types of Optical Glass Are There? 18 Classes, 16 Material Families and Applications"},"content":{"rendered":"
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Materials knowledge \u00b7 Engineering selection<\/p>\n

Two groups, 18 classes or hundreds of grades? Each answer counts something different. This guide separates optical-design classes, chemical families and applications, then compares their indicative properties and uses in two clear tables.<\/p>\n

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18 classes<\/strong>Traditional colourless optical glass<\/span><\/div>\n
16 groups<\/strong>Representative chemical families<\/span><\/div>\n
No single total<\/strong>Grades and functional classes overlap<\/span><\/div>\n<\/div>\n

This educational guide is not an inventory, supply, agency or performance claim for any listed grade. Check the specified manufacturer data and finished-part drawing before selection or processing.<\/p>\n

1. Why do the counts differ?<\/h2>\n
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Imaging glasses are grouped by refractive index nd<\/sub>, Abbe number \u03bdd<\/sub> and composition. Chemical families describe the glass network. Functional groups describe UV, IR, laser, filtering or substrate use. One material can occupy all three views, so 18 is not the total number of optical glasses. An ordinary transparent sheet also does not automatically meet optical-homogeneity, striae, bubble, stress or surface specifications.<\/p>\n

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Optical design<\/strong>Index \u00b7 dispersion \u00b7 crown\/flint<\/span><\/div>\n
Chemistry<\/strong>Silicates \u00b7 phosphates \u00b7 fluorides<\/span><\/div>\n
End use<\/strong>Imaging \u00b7 laser \u00b7 IR \u00b7 substrates<\/span><\/div>\n<\/div>\n<\/div>\n
\"Process
Process photograph: dimensional inspection of a glass component; it does not represent every material family in the tables.<\/figcaption><\/figure>\n<\/div>\n

2. The 18 traditional colourless optical-glass classes<\/h2>\n

GB\/T 903-2019 is the current Chinese standard for colourless optical glass. The names and codes below follow the public CDGM optical-glass data sheet. A class is a naming and design starting point, not one composition; each class contains multiple grades. The property directions are only for screening. Confirm nd<\/sub>, \u03bdd<\/sub>, partial dispersion and internal quality for the actual grade.<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Code<\/th>\nTraditional class<\/th>\nIndicative optical direction<\/th>\nTypical design direction<\/th>\n<\/tr>\n<\/thead>\n
FK<\/th>\nFluor crown<\/td>\nOften lower relative dispersion; check the grade<\/td>\nImaging lenses and chromatic pairing<\/td>\n<\/tr>\n
QK<\/th>\nLight crown<\/td>\nOften lower relative dispersion; check the grade<\/td>\nImaging lenses and chromatic pairing<\/td>\n<\/tr>\n
K<\/th>\nCrown<\/td>\nOften lower relative dispersion; check the grade<\/td>\nImaging lenses and chromatic pairing<\/td>\n<\/tr>\n
PK<\/th>\nPhosphate crown<\/td>\nOften lower relative dispersion; check the grade<\/td>\nImaging lenses and chromatic pairing<\/td>\n<\/tr>\n
ZPK<\/th>\nDense phosphate crown<\/td>\nOften lower relative dispersion; check the grade<\/td>\nImaging lenses and chromatic pairing<\/td>\n<\/tr>\n
BaK<\/th>\nBarium crown<\/td>\nDifferent index\/dispersion combinations<\/td>\nHigher-index imaging and layout optimisation<\/td>\n<\/tr>\n
ZK<\/th>\nDense crown<\/td>\nDifferent index\/dispersion combinations<\/td>\nHigher-index imaging and layout optimisation<\/td>\n<\/tr>\n
LaK<\/th>\nLanthanum crown<\/td>\nDifferent index\/dispersion combinations<\/td>\nHigher-index imaging and layout optimisation<\/td>\n<\/tr>\n
KF<\/th>\nCrown\u2013flint<\/td>\nDesign choices between crown and flint<\/td>\nBalance chromatic and other aberrations<\/td>\n<\/tr>\n
QF<\/th>\nLight flint<\/td>\nOften higher relative dispersion; check the grade<\/td>\nAchromatic combinations and aberration control<\/td>\n<\/tr>\n
F<\/th>\nFlint<\/td>\nOften higher relative dispersion; check the grade<\/td>\nAchromatic combinations and aberration control<\/td>\n<\/tr>\n
BaF<\/th>\nBarium flint<\/td>\nOften higher relative dispersion; check the grade<\/td>\nAchromatic combinations and aberration control<\/td>\n<\/tr>\n
ZBaF<\/th>\nDense barium flint<\/td>\nHigher-index and\/or higher-dispersion options; grade-specific<\/td>\nCompact lenses and chromatic correction<\/td>\n<\/tr>\n
ZF<\/th>\nDense flint<\/td>\nHigher-index and\/or higher-dispersion options; grade-specific<\/td>\nCompact lenses and chromatic correction<\/td>\n<\/tr>\n
LaF<\/th>\nLanthanum flint<\/td>\nHigher-index and\/or higher-dispersion options; grade-specific<\/td>\nCompact lenses and chromatic correction<\/td>\n<\/tr>\n
ZLaF<\/th>\nDense lanthanum flint<\/td>\nHigher-index and\/or higher-dispersion options; grade-specific<\/td>\nCompact lenses and chromatic correction<\/td>\n<\/tr>\n
TiF<\/th>\nTitanium flint<\/td>\nHigher-index and\/or higher-dispersion options; grade-specific<\/td>\nCompact lenses and chromatic correction<\/td>\n<\/tr>\n
TF<\/th>\nSpecial flint<\/td>\nSpecial design region; grade-specific<\/td>\nSpecific optical-design requirements<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

\u201cFluor crown\u201d is not synonymous with bulk fluoride glass. Crown and flint are design categories, not two single chemical substances.<\/p>\n

3. Sixteen representative chemical families: properties and uses<\/h2>\n

These 16 entries are a teaching framework, not an official international taxonomy, an exhaustive list or mutually exclusive groups. Boroaluminosilicates also sit within the broad silicate family; fluorophosphates are mixed systems. The table gives property directions, never a family-wide specification.<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Material family<\/th>\nProperty direction and limits<\/th>\nIndicative applications<\/th>\n<\/tr>\n<\/thead>\n
Fused silica \/ silica glass<\/th>\nLow expansion; UV\/IR transmission depends on grade, impurities and OH<\/td>\nUV windows, laser optics, semiconductor processing<\/td>\n<\/tr>\n
Silicate glass<\/th>\nBroad composition and index\/dispersion range<\/td>\nImaging, windows, industrial optics<\/td>\n<\/tr>\n
Borosilicate glass<\/th>\nSome grades offer low expansion and thermal-shock resistance<\/td>\nWindows, substrates, microfluidics, MEMS<\/td>\n<\/tr>\n
Aluminosilicate glass<\/th>\nSome compositions accept ion exchange; verify by grade<\/td>\nProtective covers, sensor windows<\/td>\n<\/tr>\n
Boroaluminosilicate glass<\/th>\nCan be low-alkali or alkali-free; stability is grade-specific<\/td>\nDisplay and electronic substrates, packaging<\/td>\n<\/tr>\n
Borate glass<\/th>\nIndex and dispersion can be tuned by composition<\/td>\nSpecialty optics and materials research<\/td>\n<\/tr>\n
Phosphate glass<\/th>\nCan host rare-earth dopants; durability varies by formula<\/td>\nLaser gain media, specialty fibres<\/td>\n<\/tr>\n
Borophosphate glass<\/th>\nMixed network; optical, thermal and chemical properties can be tuned<\/td>\nSpecialty functional-material research<\/td>\n<\/tr>\n
Germanate glass<\/th>\nSome systems suit near\/mid IR; range is composition-specific<\/td>\nIR photonics, specialty fibres<\/td>\n<\/tr>\n
Tellurite glass<\/th>\nSome systems offer high index and nonlinear response<\/td>\nIR and nonlinear photonics<\/td>\n<\/tr>\n
Heavy-metal oxide glass<\/th>\nHigh index is possible; check composition and compliance<\/td>\nHigh-index optics, specialty devices<\/td>\n<\/tr>\n
Specialty aluminate glass<\/th>\nUnlike common silicates; properties depend on composition<\/td>\nInfrared-material research<\/td>\n<\/tr>\n
Fluoride glass<\/th>\nSome grades suit IR; recheck mechanical and chemical limits<\/td>\nIR windows, specialty fibres<\/td>\n<\/tr>\n
Oxyfluoride \/ fluorophosphate glass<\/th>\nMixed oxide\u2013fluoride systems; dispersion can be tailored<\/td>\nLow-dispersion optics, luminescent devices<\/td>\n<\/tr>\n
Chalcogenide glass<\/th>\nSome compositions transmit IR; range and safety vary<\/td>\nThermal imaging, IR spectroscopy and sensing<\/td>\n<\/tr>\n
Oxynitride glass<\/th>\nSome systems have higher hardness and modulus<\/td>\nHigh-performance materials and specialty-optics research<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Silica glass is amorphous SiO\u2082, unlike crystalline quartz. \u201cAlkali-free\u201d means alkali-metal oxide content is controlled, not necessarily mathematically zero. Tellurite is an oxide glass and is not chalcogenide glass merely because it contains tellurium.<\/p>\n

4. Which specifications decide suitability?<\/h2>\n

Similar names do not imply interchangeability. Record the measurement wavelength, sample thickness, temperature range, processed condition and acceptance method in the purchasing specification.<\/p>\n

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Refractive index nd<\/sub><\/h3>\n

Index at the d spectral line near 587.6 nm; precision imaging also requires full dispersion data.<\/p>\n<\/div>\n

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Abbe number \u03bdd<\/sub><\/h3>\n

\u03bdd<\/sub>=(nd<\/sub>\u22121)\/(nF<\/sub>\u2212nC<\/sub>); F\u2248486.1 nm and C\u2248656.3 nm. A higher value generally means lower relative dispersion.<\/p>\n<\/div>\n

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Spectral transmission<\/h3>\n

Distinguish external from internal transmittance; state wavelength, thickness and surface condition before comparing percentages.<\/p>\n<\/div>\n

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Thermal expansion, CTE<\/h3>\n

State the temperature interval. Mixed-material packages also need bonding-process and thermal-budget checks.<\/p>\n<\/div>\n

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Internal and finished quality<\/h3>\n

Specify homogeneity, striae, bubbles, stress birefringence, TTV, flatness, edge condition and cleanliness.<\/p>\n<\/div>\n<\/div>\n

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<\/i><\/i><\/i>F
486.1 nm<\/span>d
587.6 nm<\/span>C
656.3 nm<\/span><\/div>\n
\u03bdd<\/sub> = (nd<\/sub> \u2212 1) \/ (nF<\/sub> \u2212 nC<\/sub>)<\/div>
Technical schematic: F, d and C are the spectral lines used for the Abbe number. It is not a measured transmission curve. A generic spectrum would be misleading without a specified grade and thickness.<\/figcaption><\/figure>\n

5. Work back from the application and processing route<\/h2>\n
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Imaging and instruments<\/h3>\n

Set wavelength, index, dispersion, homogeneity and stress limits.<\/p>\n<\/div>\n

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Laser and UV windows<\/h3>\n

Check target-wavelength absorption, damage threshold, surface defects and coating.<\/p>\n<\/div>\n

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Optical communications and sensing<\/h3>\n

Control dimensions, end faces, thermal matching and clean assembly.<\/p>\n<\/div>\n

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Semiconductors and MEMS<\/h3>\n

Check CTE, thickness\/TTV, cleanliness, dielectric data and bonding compatibility.<\/p>\n<\/div>\n

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Microfluidics and infrared<\/h3>\n

Match chemical environment or IR band to material and channel\/packaging processes.<\/p>\n<\/div>\n<\/div>\n

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\"Process
Process photograph: precision glass cutting; parameters depend on the selected grade and drawing.<\/figcaption><\/figure>\n
\"Process
Process photograph: inspection after processing; acceptance should cover dimensions, surfaces and edges.<\/figcaption><\/figure>\n<\/div>\n

6. What should a drawing-based RFQ include?<\/h2>\n
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