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QUARTZ
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Cultured crystalline quartz is mostly used for fabrication of finished
optics: laser beamsplitters, AO elements, polarizing optics, prisms, windows,
lenses in the ultraviolet. 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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Quality
grade
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Coefficient
of absorption (αmax at 190 nm)
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Coefficient
of absorption (αmax at 2800 nm)
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1
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0.010
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0.030
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2
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0.025
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0.045
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3
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0.050
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0.070
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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.
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FUSED SILICA
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Fused
Silica is amorphous, isotropic form of silicon dioxide (SiO2).
The material 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.
Fused Silica is less dispersive than cultured quartz, does not suffer
degradation when exposed to gamma or x-rays and has low coefficient
of thermal expansion, what makes it highly resistant to thermal shock.
Products manufactured: Lenses, windows, wedges, optical beamsplitters,
optical filters, prisms, etc.
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SAPPHIRE
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We supply it according to customer's specifications:
- Sapphire UV-IR windows up to 150 x 150 mm2
- Sapphire substrates
- Shaped Sapphire
- Sapphire crucibles
- Sapphire rods and wavelites (L = up to 150 mm)
- Sapphire for medical applications
- Metal coating for solding on Sapphire windows
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Undoped YAG
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Undoped Yttrium Aluminium Garnet (Y3Al5O12
or YAG) is a new substrate and optical material that can be used
for both UV and IR optics. It is particularly useful for high-temperature
and high-energy applications. The mechanical and chemical stability
of YAG is similar to that of Sapphire, but YAG is not birefringent
and is available with high optical homogenity.We provide high quality
YAG with different dimensions and specifications for the use in
industrial, medical and scientific fields. YAG is grown utilising
the Czochralsky technique. The as-grown crystals are then processed
into rods, slabs or prisms, coated and inspected per customer specifications.
YAG shows no trace absorbtion in the 2 - 3 µm region where Glasses
tend to be highly absorbent because of the strong H2O
band. |
Physical properties:
| Crystal structure |
cubic |
| Transmission range, nm |
250 - 5000 |
| Density, g/cm3 |
4.5 |
| Mohs hardness |
~8.5 |
| Specific heat, W x
s x g-1 x
°K-1 |
0.59 |
| Thermal conductivity, W
x cm-1
x °K-1 |
0.14 |
| Thermal expansion coefficient |
6.9 x
10-6 x
°K-1 |
| Thermal shock resistance,
W x m-1 |
790 |
| Termooptical factor (dn/dT),
at 633 nm |
7.3 x
10-6 x
°K-1 |
| Refractive indexes: |
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| at 0.8 µm |
1.8245 |
| at 1.0 µm |
1.8197 |
| at 1.4 µm |
1.8121 |
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Undoped Yttrium Vanadate (YVO4)
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The Yttrium Vanadate (YVO4)
falls under the category of birefringent crystals and meet all necessary
demands to be very prospective material for fibre optical communication
systems. It's ideal for optical polarizing components such as fibre optical
isolators, beam displacers and circulators.
Comparison of YVO4
with other birefringent crystals:
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YVO4
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TiO2
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CaCO3
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LiNbO3
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| Thermal expansion
coefficient |
c-axis |
11.4
x 10-6 x
°K-1
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9.2 x
10-6 x
°K-1
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26.3
x 10-6
x °K-1
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16.7
x 10-6
x °K-1
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a-axis |
4.4
x 10-6 x
°K-1
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7.1
x 10-6 x
°K-1
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5.4
x 10-6 x
°K-1
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2.0
x 10-6 x
°K-1
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| Refractive
indices |
no |
1.9447@1550
nm
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2.454@1530
nm
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1.6346@1497
nm
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2.2151@1440
nm
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ne |
2.1486@1550
nm
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2.710@1530
nm
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1.4774@1497
nm
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2.1413@1440
nm
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| Birefringence
(ne - no) |
0.2039@1550
nm
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0.256@1530
nm
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-0.1572@1497
nm
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-0.0738@1440
nm
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| Mohs hardness |
5
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6.5
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3
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5
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| Transparency range |
0.4 - 5 µm
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0.4 - 5 µm
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0.32 - 2.3 µm
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0.4 - 5 µm
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Sizes and dimensions of elements can be varied according to customer´s demand.
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SINGLE CRYSTAL AII-BVI COMPOUNDS
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CVD-TECHNOLOGY
Single crystals of II-VI compounds are grown from the vapor phase by physical transport with helium or argon and by chemical transport with hydrogen or argon-hidrogen gas mixture. Types of materials: ZnS, ZnSe, ZnTe, Zn1-xCdxS, Zn1-xCdxSe, CdSxSe1-x
CVD ZnSe has 4 - 6 times lower absorption coefficient at 10.6 µm compared
with polycrystalline ZnSe and is recommended for the usage in high power
CO2 laser optics.
CRYSTALLIZATION FROM MELT
At present three types of AIIBVIcrystals are growing with max dimensions:
- ZnSe - 50 mm dia., 50 mm in hight
- CdSe - 20 mm dia., 50 mm in hight
- CdS - 20 mm dia., 100 mm in hight
From these crystals we can fabricate:
ZnSe IR optical components, which operate as elements of high power CO2-lasers (windows, lenses, prisms, beamspliters etc.) Absorptivity at 10.6 µm is no more than 0.002 cm-1. The different coatings on the elements are available.
ZnSe oriented single crystals rods as IR electrooptical
modulators with max dimensions 5 x 10 x 45 mm3, any crystallographic
orientation, resistivity >1010 Ohm x
cm.
ZnSe oriented cubics with dimensions 10 x 10 x 10 mm3, high resistivity (>1010 Ohm x
cm).
ZnSe substrates to fabricate heterojurunctions with GaAs film (blue light emission diodes and lasers)-plates 10 x 10 mm2, 10 x 20 mm2, 10 x 30 mm2 or any other form with thickness of 1÷ 2 mm, (111) or (100) orientation, high resistivity (>1010 Ohm x cm), free of twins, EPD is 104/ cm2.
CdS oriented plates with low (<10-1 Ohm x cm) and high resistivity (>108 Ohm x cm)
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POLYCRYSTALLINE ZnSe
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Polycrystalline ZnSe is used for infrared windows, lenses and
prisms where transmission in the range from 0.5 to 20 µm is
desired. In comparison with other IR materials like Ge, Si and
GaAs, Zinc Selenide transmits in VIS spectral range that considerably
simplifies the adjustment of optical systems. |
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Polycrystalline ZnSe is less expensive and widely used for low and medium power infrared systems.
We provide the reflection/transmission capacity of the mirror coatings
by customer's order.
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SILICON,
GERMANIUM |
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Silicon (Si) is commonly used as a substrate material
for infrared reflectors and windows in the 1.5 - 8 µm region. The
strong absorption band at 9 µm makes it unsuitable for CO2-laser
transmission applications but it is frequently used for laser mirrors
because of its high thermal conductivity and low density. Silicon is also
a usefull transmitter in the 20 µm range.
Germanium (Ge) is most widely used for lenses and windows
in IR systems operating in the 2 - 12 µm range. Enviroment does not
make any problems because Germanium is inert, mechanically rugged, and
fairly hard. It is an excellent choice for multi-spectral systems and
for applications where EMI shielding is necessary. Germanium can be electrically
heated for anti-fogging or anti-icing applications.
We do not manufacture Germanium, but hold stock of Czochralsky grown material of various diameters. It can be used as a polycrystalline or as a single crystal. The purity should correspond to an electrical resistivity of at least 20 to 30 Ohm/cm, either p- or n-type to avoid absorption bands. The high retractive index makes AR-coating essential.
The deliveries from ground to finished Si- or Ge-blanks as well
as processed uncoated or AR-coated optical elements are possible.
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TELLURIUM |
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MAIN PROPERTIES:
| Transparency
range, µm |
3.5 - 36 |
| Point group |
32m |
| Lattice parameters,
Å |
a = 4.495,
b = 3.74, c = 5.912 |
| Mohs hardness |
2 - 2.5 |
| Density, g/cm3 |
6.25 |
| Refractive
indexes: |
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at 5.0 µm |
no
= 4.864; ne = 6.316 |
| at 10.6 µm |
no
= 4.792; ne = 6.247 |
| at 14 µm |
no
= 4.775; ne = 6.230 |
| at 28 µm |
no
= 4.716; ne = 6.183 |
| Non-linear
coefficient at 10.6 µm, pm/V |
d11
= 650 |
| Optical damage
threshold, MW/cm2 |
20 - 40 (at
10.6 µm, 150 ns) |
| Thermal expansion
coefficient , at 293 °K: |
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parallel to z-axis |
1.6 x 10-6
x °K -1 |
| perpendicular
to z-axis |
27.2 x 10-6
x °K -1 |
| Thermal conductivity,
mW x cm-1
x °K -1 |
4000 |
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OPTICAL CRYSTALS
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Optical crystals, such as CaF2, BaF2, MgF2, LiF, NaCl, KCl, KBr, etc, are widely used in IR optics and UV optics. High transparency and low loss optical windows, prisms, lenses, achromatic lenses and parallel planes have been fabricated in these optical materials.
We supply high quality, low cost and large size crystals based on the
Czochralsky and Bridgman Methods. These crystals are widely applied to
the entire optical wavelength range, from vacuum ultraviolet (0.11 µm)
to far infrared (40 µm). MolTech is ready to meet customers' various
requirements for dimensions and other specifications.
We supply following materials:
| Magnesium
Fluoride (MgF2) |
Calcium
Fluoride (CaF2) |
| Barium
Fluoride (BaF2) |
Lithium
Fluoride (LiF) |
| Potassium
Bromide (KBr) |
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Not only as-grown and as-cut boule but also finished optical components
are available.
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Magnesium Fluoride (MgF2)
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Magnesium Fluoride (MgF2)
is the only optical material combining wide spectral transmittance band
with birefringince phenomenon and satisfactory thermal expansion coefficient
for isotropic crosssection. It is used for UV-radiation sources and receivers
windows manufacture; for optical elements of interference-polarization
filters, as laser resonator optics elements in quantum electronics and
as active material in IR and submillimeter band.
Physical Properties:
| Transmission
range (thickness 10 mm), µm |
0.11
- 8.0 |
| Crystal
structure |
tetragonal |
| Lattice
constant, Å |
a
= 4.64; c = 3.06 |
| Density,
g/cm3 |
3.177 |
| Mohs
hardness |
6 |
| Refractive
indexes |
ne
= 1.3852; no = 1.3796 |
| Solubility,
g/100 g water at 18°C |
7.6 x
10-3 |
Specifications for MgF2windows:
| Surface
quality, scratch - dig |
60
- 40 |
| Clear
aperture |
90%
of diameter |
| Diameter
tolerance, mm |
+0.0
/ -0.1 |
| Thickness
tolerance, mm |
±
2 |
| Flatness |
λ/4
(633 nm) |
| Parallelism,
arc min |
3 |
| Δ
N |
< 0.5 x
10-5 |
| Optical
losses, cm-1 |
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| MgF2-UV
(200 nm) |
<
0.07 |
| MgF2-UV
(500 nm) |
<
0.02 |
MgF2 lenses and prisms are available at request.
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Calcium Fluoride (CaF2)
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The Calcium Fluoride (CaF2) crystals are transparent in wide spectrum band. The product finds use in windows, lenses operating in UV and IR spectrum band.
Laser Use: Calcium Fluoride is also used as a host lattice for laser crystals.
Due to its composition CaF2 has a much longer
useful life than most materials when used in fluorine environment.
Physical Properties:
| Transmission
range (thickness 10 mm), µm |
0.15
- 9.00 |
| Crystal
structure |
cubic |
| Lattice
constant, Å |
a
= 5.462 |
| Density,
g/cm3 |
3.18 |
| Mohs
hardness |
4 |
| Refractive
index, at 0.13 - 9.43 µm |
1.6921
- 1.3161 |
| Solubility,
g/100 g water at 18°C |
1.6 x
10-3 |
Specifications for CaF2windows:
| Surface
quality, scratch - dig |
60
- 40 |
| Clear
aperture |
90%
of diameter |
| Diameter
tolerance, mm |
+0.0
/ -0.1 |
| Thickness
tolerance, mm |
±
2 |
| Flatness |
λ/4
(633 nm) |
| Parallelism,
arc min |
3 |
| Δ
N |
< 0.5 x 10-5 |
| Reflection loss at 4 µm,% |
5.6
(two surfaces) |
CaF2 lenses and prisms are available at request.
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Barium Fluoride (BaF2)
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The Barium Fluoride (BaF2) crystals are transparent in wide spectrum band.
The product finds use in windows, lenses of special types of objectives, as mirrors substrate in optical systems
operating in UV and IR spectrum band.
Physical Properties:
| Transmission
range (thickness 10 mm), µm |
0.15
- 15.00 |
| Crystal
structure |
cubic |
| Lattice
constant, Å |
a
= 6.196 |
| Density,
g/cm3 |
4.89 |
| Mohs
hardness |
3 |
| Refractive
index, at 1.0 µm |
n
= 1.4686 |
| Solubility,
g/100 g water at 25°C |
0.12 |
Specifications for BaF2windows:
| Surface
quality, scratch - dig |
60
- 40 |
| Clear
aperture |
90%
of diameter |
| Diameter
tolerance, mm |
+0.0
/ -0.1 |
| Thickness
tolerance, mm |
±
2 |
| Flatness |
λ/4
(633 nm) |
| Parallelism,
arc min |
3 |
| Δ
N |
< 0.5 x
10-5 |
| Optical
losses, cm-1 |
|
|
at 0.2 µm |
<
0.20 |
|
at 0.4 µm |
<
0.08 |
|
at 10.6 µm |
<
0.13 |
BaF2 lenses and prisms are available at request.
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Lithium Fluoride (LiF)
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Lithium fluoride (LiF) crystals suit well for manufacturing optical elements
(mirrors, windows, lenses) for UV, visible and IR applications. These
crystals are optically isotropic, middle hard, hygroscopic, unsolvable
in water.
Physical Properties:
| Transmission
range (thickness 10 mm), µm |
0.12
- 6.50 |
| Crystal
structure |
cubic |
| Lattice
constant, Å |
a
= 4.026 |
| Density,
g/cm3 |
2.60 |
| Mohs
hardness |
4 |
| Refractive
index, at 1.0 µm |
n
= 1.387 |
Specifications for LiF windows:
| Surface
quality, scratch - dig |
60
- 40 |
| Clear
aperture |
90%
of diameter |
| Diameter
tolerance, mm |
+0.0
/ -0.1 |
| Thickness
tolerance, mm |
±
2 |
| Flatness |
λ/4
(633 nm) |
| Parallelism,
arc min |
3 |
LiF lenses and prisms are available at request. |
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Potassium Bromide (KBr)
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Potassium Bromide (KBr) is used as IR spectroscopic components, beamsplitters, for CO2
-lasers. KBr is water soluble and must be protected against moisture degradation of polished surfaces. The material
cleaves readily, and can be used at temperature up to 300 °C. Irradiation of KBr produces color centers.
Physical Properties
| Transmission
range (thickness 10 mm), µm |
0.21
- 28.00 |
| Crystal
structure |
cubic |
| Lattice
constant, Å |
a
= 6.598 |
| Density,
g/cm3 |
2.75 |
| Mohs
hardness |
1.5 |
| Refractive
index, at 9.724 µm |
n
= 1.5269 |
| Reflection
loss at 10 µm, 2 surfaces |
8.4
% |
| Solubility,
g/100 g water at 0°C |
53.48 |
Specifications for KBr windows:
| Surface
quality, scratch - dig |
60
- 40 |
| Clear
aperture |
90%
of diameter |
| Diameter
tolerance, mm |
+0.0
/ -0.1 |
| Thickness
tolerance, mm |
±
2 |
| Flatness |
λ/4
(633 nm) |
| Parallelism,
arc min |
3 |
Potassium Bromide is grown in diameter up to 300 mm. KBr lenses and prisms are
available at request. |
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NaCl, KCl, CsI
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Sodium Chloride (NaCl) is used for windows, lenses and prisms where transmission
in the 0.25 - 16 µm range is desired. Because of its low absorption,
Sodium Chloride is being used in high power laser systems. Polished surfaces
must be protected from moisture by exposing to only dry atmosphere or
by using a heating element to maintain the Sodium Chloride above the ambient
temperature. Sodium Chloride can be used up to 400°C. The material is
sensitive to thermal shock. Irradiation generates color centers.
Potassium Chloride (KCl) is used for infrared windows, lenses and prisms when transmission in the 0.3 - 20 µm range is desired (transmission extends beyond that of Sodium Chloride). Potassium Chloride is soluble in water and polished surfaces must be protected from moisture. Maximum use temperature is 400°C.
Cesium Iodide (CsI) is useful for infrared having transmission through the visible out to 70 µm in a 2 mm thickness. It is principally used for infrared prisms and cell windows. Cesium Iodide is also furnished as Thallium activated Cesium Iodide for scintillation crystals. Being relatively soft, this material has found application in satellite-borne radiation detectors, which must withstand extreme shock and vibration along with rapid temperature changes. Cesium Iodide precipitated powders are used in solid phase pelleting of samples for infrared spectroscopy.
Advantages offered are: extended transmission range and
low water absorption.
Laser Use:CsI is used in the far infrared as a beamsplitter or as interferometer plates.
Influence of Environment -- Moisture: Cesium Iodide is
highly water soluble and polished faces of this material may be damaged
by moisture in the atmosphere when relative humidity is higher than 35%.
Handling -- Orientation: Orientation must be done by
x-ray techniques.
Cleavage:Cesium Iodide does not cleave at room temperature.
Cutting and Polishing: Cesium Iodide can be cut with
a band saw. Standard polishing techniques can be used. |
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KRS-5, KRS-6
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Thallium Halogenide crystals (KRS-5, KRS-6) are designed for transmission,
refraction and focusing of visible and infrared radiation.
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Wide transparence range, radiation, thermal and vibrational stability, low water solubility make these crystals
valuable for applications in optical devices working in atmosphere conditions and outer space without special
protection. Low absorbtion in MID-IR and large refractive index make these crystals suitable for internal reflection
elements.
Main properties:
|
KRS-5 |
KRS-6 |
| Chemical composition |
TlBr - 40% |
TlBr - 30% |
|
Tll - 60% |
TlCl - 70% |
| Spectral transparency
range, µm |
0.56 - 50 |
0.4 - 40 |
| Density, g/cm3 |
7.37 |
7.19 |
| Water solubility
at 20°C, g/100 g |
0.05 |
0.32 |
| Optical transmission,
% |
|
|
| at 0.633 µm |
> 60 |
> 65 |
| at 2 - 25 µm |
> 68 |
> 72 |
| Absorbtion
at 10.6 µm, cm-1 |
< 1 x
10-3 |
< 1 x
10-3 |
| Refractive
index, at 0.633 - 10.6 µm |
2.57 - 2.37 |
2.33 - 2.17 |
| Max. sizes,
mm |
dia.= 100,
length=100 |
dia.= 150,
length = 100 |
The deliveries from ground blanks to finished as well as processed optical elements are possible. |
