18 Dec 2020 Calcium fluoride(CaF2) is a very important optical functional crystal, which has good optical properties, mechanical properties and chemical stability. It can be used as optical crystal, laser crystal and inorganic scintillation crystal. It has a wide transmittance range (0.125-10 μm), and is widely used as optical medium from vacuum ultraviolet to mid infrared. CaF2 crystal is an ideal optical material for achromatic lenses because of its special refractive index and relative dispersion. At present, deep UV excimer laser lithography is developing from 193 nm to 121 nm. CaF2 single crystal has the advantages of good ultraviolet transmittance, high laser damage resistance threshold, low stress birefringence and high refractive index, which makes it the best choice for the research of deep UV excimer laser lithography. In terms of laser applications, laser diode pumped CaF2 crystals activated by Er3+, Tm3+, Yb3+ and other 3-valent rare earth ions were obtained at room temperature.
Parameter
Material and Specifications
|
Orientation
|
[100] or [001] < ±0.5°
|
|
Orientation Tolerance
|
< 0.5°
|
|
Parallelism
|
<20〞
|
|
Perpendicularity
|
5ˊ
|
|
Surface Quality
|
10-5 (MIL-O-13830A）
|
|
Wavefront Distortion
|
<λ/4@633 nm
|
|
Surface Flatness
|
<λ/8 @633 nm
|
|
Clear Aperture
|
>90%
|
|
Thickness/Diameter Tolerance
|
±0.05 mm
|
Physical and Chemical Properties
|
Crystal System
|
Isometric
|
|
Habit
|
Cubic, massive
|
|
Space Group
|
Fm3m
|
|
Class (H-M)
|
m3m (4/m 3 2/m) – Hexoctahedral
|
|
Lattice Constants
|
5.4626 Å
|
|
Z
|
4
|
|
Streak
|
White
|
|
Density
|
3.175…3.56g/cm3
|
|
Melting Point
|
1418°C
|
|
Thermal Conductivity /(W·m-1·K-1@25°C)
|
9.71@[111]
|
|
Heat Capacity/(J ·(kg·K)-1)
|
854
|
|
Thermal Expansion /（10-6·K-1@25°C ）
|
18.9
|
|
Young`s Modulus /GPa
|
75.8
|
|
Tenacity
|
Brittle
|
|
Cleavage Quality
|
Perfect, perfect and easy
|
|
Hardness (Mohs)
|
4
|
|
Fracture
|
Conchoidal
|
Optical characteristics
|
Transmission Range
|
0.125 – 10 µm
|
|
Refractive Index
|
1.432-1.436
|
|
Reflective Loss
|
2.89@4µm
|
|
Optical Character
|
Isotropic
|
|
Surface Relief
|
Moderate
|
|
Birefringence
|
None
|
|
Pleochroism
|
Absent
|
|
Dispersion
|
0.007
|
|
Poisson Ratio
|
0.29
|
|
Dielectric Constant
|
6.76
|
Index of Refraction
|
λ(μm)
|
n
|
λ(μm)
|
n
|
λ(μm)
|
n
|
|
0.18
|
1.51
|
0.32
|
1.45
|
5.82
|
1.39
|
|
0.19
|
1.50
|
0.43
|
1.44
|
6.20
|
1.38
|
|
0.21
|
1.49
|
0.88
|
1.43
|
6.71
|
1.37
|
|
0.22
|
1.48
|
2.67
|
1.42
|
7.00
|
1.36
|
|
0.24
|
1.47
|
3.94
|
1.41
|
7.53
|
1.35
|
|
0.27
|
1.46
|
5.01
|
1.40
|
8.22
|
1.34
|
Spectrum
Feature
- Excellent transmission from 125nm to 10um
- Good optical properties, mechanical behavior and chemical stability
- Anisotropy, soft and brittle, high coefficient of thermal expansion and easy cleavage
- Special refractive index and relative dispersion value
- Soluble in acids
- Good ultraviolet transmittance, high laser damage resistance threshold, low stress birefringence and high refractive index
Application
- Optical crystal, laser crystal(IR, UV, VUV)
- Optical media and optical material
- Best material for the study of deep UV excimer laser lithography
- Substrate, optical waveguide
- IR analytic, astronomical-und camera lenses and optics for Excimer laser
|
