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Crystal
quartz (SiO2) is a very useful material for fabrication of finished
optics: laser beamsplitters, AO elements, polarizing optics, prisms,
windows, lenses in the ultraviolet because of its high UV, VIS and NIR
transmittance, birefringence, ability to rotate plane polarized light,
high damage threshold and resistance to scratching. The optical grade
material is featured by the highest possible transmittance throughout
the range of 190 - 2900 nm, virtual freedom from bubbles and inclusions.
Grown boules are Z - crystals and about 100 mm in the direction down
the optic axis that limits corresponding dimension in an optical part.
Silicon dioxide occurs naturally as sand or rock, and when
melted, the resulting product is called Fused Quartz. If the
silicon dioxide is synthetically derived, the material is often called
Fused Silica. Fused Quartz is very pure, has a high chemical
resistance, good thermal shock resistance and is very strong in compression.
The low thermal expansion coefficient makes it ideal for mirrors and
optical flats. It is used for viewing windows, being transparent to
wavelengths from around 0.2 to 3.5 µm, insulators for electronic
applications and for semi-conductor manufacturing. |
Material
properties of the Crystal Quartz:
|
Quality
grade |
Coefficient of absorption (±max at 190 nm), cm-1
|
Coefficient
of absorption (±max at 2800 nm), cm-1
|
|
1
|
0.010
|
0.030
|
|
2
|
0.025
|
0.045
|
|
3
|
0.050
|
0.070
|
Properties:
| Chemical
Formula |
SiO2 |
| Positive
uniaxial crystal |
ne
> no |
| Density,
g/cm3 |
2.65 |
| Mohs
Hardness |
7 |
| Heat
Capacity at 300K, J/kg·K |
733 |
| Thermal
Expansion Coefficient at 300 K, 10-6· K-1 |
a||
= 7.64, a^= 14.00 |
| Thermal
conductivity at 300 K, W/(m×k) |
æ||
= 9.5, æ^= 6.10 |
| |
æ||
= 9.5, æ^= 6.10 |
|
Refractive
indices at T = 291°K
|
Wavelength
|
no
|
ne
|
Wavelength
|
no
|
ne
|
|
193,6
|
1,65999
|
1,67343
|
706,5
|
1,540488
|
1,549472
|
|
250,3
|
1,60032
|
1,61139
|
766,5
|
1,539071
|
1,548005
|
|
303,4
|
1,576955
|
1,58720
|
844,7
|
1,537525
|
1,54640
|
|
340,4
|
1,56747
|
1,577385
|
1000,0
|
1,53503
|
1,54381
|
|
410,2
|
1,556502
|
1,566031
|
1300,0
|
1,53102
|
1,53962
|
|
467,8
|
1,551027
|
1,560368
|
1529,6
|
1,52800
|
1,53646
|
|
508,6
|
1,548229
|
1,557475
|
1600,0
|
1,52703
|
1,53545
|
|
546,1
|
1,546174
|
1,555350
|
1800,0
|
1,52413
|
1,53242
|
|
627,8
|
1,542819
|
1,551880
|
2058,2
|
1,51998
|
1,52814
|
|
Max. available size:
100 mm along axis <100> and <010> and <001> axis. Quartz elements which
we supply are manufactured as a rule according to customer's specifications.
Material
properties of the Fused Silica:
| Apparent
porosity ( % ) |
0 |
| Density
( g cm-3 ) |
2.2 |
| Refractive
index |
1.46 |
| Useful
optical transmission range |
180 - 2500
nm |
| Water
absorption - saturation ( % ) |
0 |
| Dielectric
constant |
3.8 |
| Dielectric
strength ( kV mm-1 ) |
25-40 |
| Volume
resistivity ( Ohmcm ) |
1018
@ 25°C |
| Compressive
strength ( MPa ) |
1100 |
| Hardness
- Knoop ( kgf mm-2 ) |
820 |
| Hardness
- Vickers ( kgf mm-2 ) |
1000 |
| Shear
strength ( MPa ) |
70 |
| Tensile
modulus ( GPa ) |
72-74 |
| Tensile
strength ( MPa ) |
48 |
| Coefficient
of thermal expansion ( x10-6 K-1 ) |
0.54
@ 20-1000°C |
| Melting
point (°C ) |
1715 |
| Specific
heat ( J K-1 kg-1 ) |
670-740
@ 25°C |
| Thermal
conductivity ( W m-1 K-1 ) |
1.46
@ 20°C |
| Upper
continuous use temperature ( °C ) |
1100-1400 |
Fused Silica has high homogenity
and good transmission in the ultraviolet, visible and infrared spectral
regions. Depending on transmission range, there are UV and IR Fused
Silica grades: the useful range of UV grade is 0.17 - 2 µm and of
IR grade is 0.23 - 3.5 µm. Products manufactured: Lenses,
windows, wedges, optical beamsplitters, optical filters, prisms, etc.
Cultured crystalline quartz
is mostly used. The useful transmission range is represented from
0.18 µm to 2.8 µm by three grades of optical quartz defined
by optical absorption.
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