| Code | Material | Wavelength | Aperture | Unit Price | Delivery | Cart |
|---|---|---|---|---|---|---|
| 2116-001 | Calcite | 800/400nm | 12mm | $315 | 4 weeks | |
| 2116-002 | Calcite | 800/400nm | 12mm | $315 | 4 weeks | |
| 2116-003 | Calcite | 800/400nm | 12mm | $315 | 4 weeks | |
| 2116-004 | Calcite | 800/400nm | 12mm | $315 | 4 weeks | |
| 2116-005 | Calcite | 1030/515nm | 12mm | $315 | 4 weeks | |
| 2116-006 | Calcite | 1030/515nm | 12mm | $315 | 4 weeks | |
| 2116-007 | Calcite | 1030/515nm | 12mm | $315 | 4 weeks | |
| 2116-008 | Calcite | 1030/515nm | 12mm | $315 | 4 weeks | |
| 2116-009 | α-BBO | 600/300nm | 12mm | $375 | 4 weeks | |
| 2116-010 | α-BBO | 1030/515nm | 12mm | $315 | 4 weeks |
The group velocity is different for different wavelength, it is called group velocity mismatch (GVM), and then a time delay is introduced between fundamental and second harmonic generated (SHG) wavelength, in order to compensate this time delay, an time delay compensator with orthogonal polarizations are often used. Calcite crystals and alpha-BBO crystals are most popular materials to make the time delay compensators. By rotation of compensators, the time delay could be adjusted, the listed delay range are based on a rotation range of +/-12°.
Hangzhou Shalom EO offers Group Velocity Delay Compensators for femtoline lasers, with wavelength couples of 800nm/400nm, 1310nm/515nm and 600nm/300nm, made of Calcite crystals and Alpha-BBO crystals.
Common Specifications:
| Materials | Calcite or alpha-BBO | Orientation Tolerance | +/-0.5° |
| Flatness | λ/4@633nm | Transmission Wavefront Distortion | λ/4@633nm |
| Surface Quality | 20/10 S/D | Parallelism | <30 arc sec |
Basic Properties of Calcite:
| Density | 2.7 g/cm3 | Melting Point | 730℃ |
| Mohs Hardness | 3 | Transparency Range | 350-2300nm |
| Thermal Expansion Coefficients（/℃） | aa=24.39×10-6/K ac=5.68×10-6/K | Refractive Index | no=2.260 nε=2.142 |
| Damage Threshold | >1GW/cm2 | Sellmeier Equation (λ in μm) | no2=2.69705 + 0.0192064/(λ2-0.01820) - 0.0151624λ2 ne2=2.18438 + 0.0087309/(λ2-0.01018) - 0.0024411λ2 |
Basic Properties of Alpha-BBO Crystal:
| Transparency Range | 190-3500nm | Density | 3.85g/cm3 |
| Hygroscopic Susceptibility | low | Mohs Hardness | 4.5 |
| Damage Threshold | >1GW/cm2 | Sellmeler Equation(λ in μm) | no2 = 2.7471+0.01878/(λ2 -0.01822)-0.01354λ2 ne2 = 2.37153+0.01224/(λ2 -0.01667)-0.01516λ2 |
