鍺材料
Germanium (Ge)
鍺是一種用途廣泛的紅外材料，呈灰白色，不吸濕，無毒，導熱性很好，擁有優(yōu)秀的表面硬度和良好的強度。鍺材料通常用在2至14 微米范圍光學系統(tǒng)中。在3-5um和8-14um波長兩個紅外大氣窗口具有優(yōu)良的透過性能。僅是拋光的鍺單晶片，其透過率可達到46-48%；經(jīng)過鍍增透膜后，其透過率可達到95-98%。在2-6um范圍內吸收幾乎與產(chǎn)品厚度無關，6-12um范圍內，吸收隨產(chǎn)品厚度與波長增加而增加。P型鍺對紅外輻射的吸收較大，故紅外系統(tǒng)多使用N型鍺。鍺作為一種紅外光學材料的缺點是：隨著溫度增高，吸收會增強。鍺光學元件一般限制在低于100瓦的功率下工作，在更高的功率下將容易發(fā)生熱透鏡效應和熱失控效應。如果能使光學元件表面清潔無污染的，并得到合理充分散熱，這些危害可減到最小程度。
| 光學性能 | 透光范圍 | 1.8-23 μm | 機械性能 | 楊氏模量 | 100.0 GPa |
| Transmission Range | Young's Modulus | (14 x 106 psi) | |||
| 體吸收系數(shù) | ≤ 0.03 cm-1 | 斷裂模數(shù) | 93.0 MPa | ||
| Bulk Absorption | Rupture Modulus | (13,000 psi) | |||
| Coefficient | @ 10.6μm |
Mechanical Properties |
努氏硬度 | 693.0 kg/mm2 | |
| Optical Properties | 折射率溫度系數(shù) | 408 x 10-6/°C | Knoop Hardness | ||
| Temp. Change of | 泊松比 | 0.27 | |||
| Refractive Index | @ 10.6μm | Poisson's Ratio | |||
| 折射率的不均勻性 | < 4.89×10-5 | 物理性能 | 介電常數(shù) | 16 | |
| Refractive Index | Permittivity | ||||
| Non-homogeneity | @ 632.8 nm | 熔點oC | 937.4 | ||
| 熱學性能 | 導熱率 | 0.59 W/cm/°C | Melting Point | ||
| ThermalConductivity | 密度 Density | 5.323 g/cm3 | |||
| W/cm/°C @ 20°C | 晶向 crystal | <100>、<110>、<111> | |||
| 比熱 | 0.31J/g/°C | orientation | |||
| Thermal Properties | Specific Heat |
Physical Properties |
電阻率(Ωcm） | 5-40Ω.CM | |
| 線性膨脹系數(shù) | 5.7 x 10-6/°C | Resistivity | |||
| Linear Expansion | 導電型號Condu- |
N-type |
|||
| Coefficient | @ 20° C | ctive models |
鍺材料折射率（n）
（20°C室溫條件）
| 光學折射率 |
Wavelength |
折射率 |
Wavelength |
折射率 |
Wavelength |
折射率 |
Wavelength |
折射率 |
||||||||
|
(μm) |
n |
(μm) |
n |
(μm) |
n |
(μm) |
n |
|||||||||
|
2.2 |
4.0879 |
5.0 |
4.0160 |
7.8 |
4.0061 |
10.6 |
4.0028 |
|||||||||
|
2.4 |
4.0732 |
5.2 |
4.0149 |
8.0 |
4.0057 |
10.8 |
4.0026 |
|||||||||
|
2.6 |
4.0599 |
5.4 |
4.0139 |
8.2 |
4.0053 |
11.0 |
4.0025 |
|||||||||
|
2.8 |
4.0523 |
5.6 |
4.0128 |
8.4 |
4.0049 |
11.2 |
4.0024 |
|||||||||
|
3.0 |
4.0451 |
5.8 |
4.0118 |
8.6 |
4.0044 |
11.4 |
4.0023 |
|||||||||
|
Indices of Refraction (n) |
3.2 |
4.0399 |
6.0 |
4.0107 |
8.8 |
4.0042 |
11.6 |
4.0023 |
||||||||
|
3.4 |
4.0311 |
6.2 |
4.0097 |
9.0 |
4.0040 |
11.8 |
4.0022 |
|||||||||
|
3.6 |
4.0289 |
6.4 |
4.0092 |
9.2 |
4.0038 |
12.0 |
4.0021 |
|||||||||
|
3.8 |
4.0267 |
6.6 |
4.0087 |
9.4 |
4.0036 |
12.2 |
4.0020 |
|||||||||
|
4.0 |
4.0245 |
6.8 |
4.0083 |
9.6 |
4.0034 |
12.4 |
4.0020 |
|||||||||
|
4.2 |
4.0223 |
7.0 |
4.0079 |
9.8 |
4.0033 |
12.6 |
4.0019 |
|||||||||
|
4.4 |
4.0205 |
7.2 |
4.0074 |
10.0 |
4.0031 |
12.8 |
4.0019 |
|||||||||
|
4.6 |
4.0189 |
7.4 |
7.0070 |
10.2 |
4.0030 |
13.0 |
4.0018 |
|||||||||
|
4.8 |
4.0172 |
7.6 |
7.0066 |
10.4 |
4.0029 |
- |
- |
|||||||||
鍺材料透過率曲線
Germanium Transmission
|
