Copper (Cu)
Oxygen free high quality copper (OFHC) is used as a substrate material for the IR laser mirrors including cooled ones for the high-power laser systems.
Copper features high thermal conductivity to ensure maximum beam quality under extreme stress. Copper mirrors should also be well heatsinked. They are not recommended for low power applications since they are difficult to polish and, consequently, not inexpensive. Copper is also very soft material and scratches very easily. Great care must be taken when cleaning these mirrors even though they are coated with protective coating. 99.97% of pure copper is contained in OFHC and maximum quantity of oxygen does not exceed 0.001%.
BASE PROPERTIES
|
PARAMETER |
|
VALUE |
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| OPTICAL |
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| |
Thermal Radiation Coefficient |
|
0.025 at 3 - 20 µm at 293 K |
|
| |
Threshold of surface destruction |
|
21 ... 24 J/cm2 at 10.6 µm, t =1.5 ms, E=500 J |
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| |
Index of Absorption |
|
0.0123 cm-1 at 10.6 µm at 293 K |
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| |
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| PHYSICAL |
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| |
Density |
|
8.90 g/cm3 at 293 Ê |
|
| |
Melting Point |
|
1353 ... 1359 Ê |
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| |
Heat of Melting |
|
209 ... 217 kJ/kg |
|
| |
Thermal Conductivity |
|
399 Wm-1K-1 at 293K |
|
| |
Thermal Expansion |
|
16.6 x 10-6/°C at 293 Ê |
|
| |
Brinell Hardness |
|
450 ... 1100 MPa |
|
| |
Specific Heat Capacity |
|
384 J/(kg K) at 293 Ê |
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| |
Young’s Modulus (E) |
|
129.5 GPa |
|
| |
Shear Modulus (G) |
|
45.5 GPa |
|
| |
Poisson Ratio |
|
0.350 |
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| |
Resistivity |
|
1.724 õ 10-6 Ohm x cm at 293 K |
|
REGULAR REFLECTANCE
| |
Wavelength, µm |
0.251 |
0.288 |
0.300 |
0.305 |
0.326 |
0.357 |
0.385 |
0.400 |
0.420 |
0.450 |
|
|
Regular Reflectance |
0.259 |
0.243 |
0.250 |
0.253 |
0.249 |
0.273 |
0.286 |
0.310 |
0.327 |
0.370 |
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| |
Wavelength, µm |
0.488 |
0.500 |
0.550 |
0.600 |
0.650 |
0.694 |
0.760 |
0.800 |
1.060 |
|
|
|
Regular Reflectance |
0.430 |
0.440 |
0.477 |
0.718 |
0.800 |
0.830 |
0.831 |
0.886 |
0.901 |
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Wavelength, µm |
2.000 |
3.000 |
4.00 |
5.00 |
7.00 |
9.00 |
10.60 |
11.00 |
14.00 |
|
|
|
Regular Reflectance |
0.955 |
0.931 |
0.973 |
0.979 |
0.983 |
0.984 |
0.985 |
0.984 |
0.979 |
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