Calcite is well - known material for polarization optics. Due to structural anisotropy it has two refractive indices. So it divides an entering beam of monochromatic light into two beam having opposite polarization. This phenomenon is used to build polarization components. As the difference in the two refractive indices is very large calcite has become the most popular crystal in polarization applications.
Del Mar Ventures offers optical elements made of optical grade natural Calcite. Three different grades of natural Calcite are available depending on used optical range: UV grade - for 0.22 - 1.9 mm, colorless material, Visible - for 0.4 - 1.9 mm, colorless or light yellow colored material, and IR grade, yellow coloration is acceptable.
Within each grade material is classified to striation and scatter grades. Striation grades (A, B, C) are based on requirements close to MIL-G-174 B standard. Scatter grades (1, 2, 3) are based on the inspection of the material with 5 mW HeNe laser beam.
Typical products are: rectangular and round shaped plates, wedges, cubes.
| Orientation | to customer’s specs ± 20 arc. min. |
|---|---|
| Scratch/Dig | 60/40 (up to 20/10) |
| Flatness | l (up to l /4) |
| Parallelism | 3 arc.min (up to 10 arc. sec.) |
| Sizes | from 3 x 3 x 3 mm to 30 x 30 x 30 mm |
| AR coating are available on request. | |
| Chemical Formula | CaCO3 |
|---|---|
| Crystal Structure | Rhombohedral |
| Density, g/cm3 | 2.7 - 2.9 |
| Melting point, ° C | 1612 |
| Mohs Hardness | 3.0 |
| Heat Capacity, cal / g · K, at 20 ° C | 0.20 |
| Thermal Expansion Coefficient, 10-6 K-1 | a|| = 24.5 |
| a^= 5.7 | |
| Thermal conductivity, cal / cm · S · K | ć|| = 0.0090 |
| ć^= 0.0083 | |
| Transmission Range, microns | 0.24 - 1.90 |
| l, mm | 0.312 | 0.508 | 0.670 | 1.097 | 1. 497 |
|---|---|---|---|---|---|
| no | 1.714 | 1.665 | 1.654 | 1.642 | 1.635 |
| ne | 1.511 | 1.490 | 1.484 | 1.479 | 1.477 |
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