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ULE™ Ultra Low Expansion Glass

Speciality zero expansion glass ceramics

Special Properties

  • Almost no thermal expansion
  • Very high temperature shock resistance
  • High operating temperature

Typical Applications

  • Ultra low expansion substrates
  • Length standards
  • Lightweight honeycomb mirror mounts
  • Machine tool reference blocks
  • Solid and lightweight mirror blanks
  • Astronomical telescopes
  • Precision measurement technology
  • Space satellite applications
  • Laser cavities
  • Precision gyroscopes

Ultra Low Expansion titanium silicate glass ULE™ is made by flame hydrolysis. ULE™ raw material is made by Corning and comes in large blocks (boules), which allow the manufacturing of components with almost any shape or dimension. The material is characterized by superior dimensional stability, which results from the essentially zero expansion at room temperature. The homogeneity of the thermal expansion of ULE™ within each boule is typically less than 15 ppb/°C, radially and axially. Measuring of the thermal coefficient of expansion of ULE™ can be done by a non-destructive ultrasonic method. The material is used in different applications of space technology, astronomy, precision mechanical machines, lasers and laser cavities. Also in scientific applications, the material is often used due to its particular properties. Components with dimensions of only some millimeters, up to several meters can be fabricated from this extraordinary glass material.

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Refractive Index

  • nD = 1,4828 (589nm)
    nF = 1,4892 (486nm)


  • 2,21 g/cm3 (25°C)

Coefficient of Thermal Expansion (5-35°C)

Thermal Properties

  • Softening Point : 1490°C
  • Annealing Point : 1000°C
  • Strain Point : 890°C

Chemical Properties

(at 95°C)

Duration of Test

Weight Loss

5% HCl
< 0,01
5% NaOH
0,02N Na2CO3
5% H2SO4
< 0,01
< 0,01

Electrical Properties

  • Dielectric Constant : 3,99 (100Hz ; 25°C)
  • Loss Factor : 0,00005 (100Hz ; 25°C)


Surface Quality

All given details and specifications are mean reference values and are not guaranteed. In addition, please consider our "Notes on technical specifications"