K9 (BK7) has excellent mechanical properties and very low air bubbles and impurities, good scratch resistance. Because of its chemical stability, no special treatment grinding and polishing. Used in optoelectronics, microwave technology, and many other areas of diffractive optical elements.
k9(bk7) Glass of Performance
| Nature of optical | Through rate |
|---|---|
| Index of refraction | 1.51680 |
| Abbe number | 63.96 |
| Mechanical properties | Standard value |
|---|---|
| Density | 2.51g/cm3 |
| Knoop hardness HK 100 | 610kg/mm2 |
| Young's modulus E | 82 x 103kN/mm2 |
| Poisson's ratio μ | 0.21 |
| Thermal properties | Standard value |
|---|---|
| Softening point | 719°C |
| Annealing Point | 657°C |
| Strain point | 624°C |
| Thermal conductivity | 1.1W/m.°C |
| Specific heat | 879J/kg.°C |
| Coefficient of thermal expansion | 7.1×10E-6/K |
| Chemical performance | Standard value |
|---|---|
| Hydrolysis | 2 Level |
| Acid | 1 Level |
| Alkaline | 2 Level |
k9(bk7) Glass's Spectra
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