Time delay compensators are made of calcite crystals or alpha-BBO crystals to compensate the time delay between two specified wavelengths with orthogonal polarizations. The time delay between the fundamental pulses and harmonic pulses is introduced in a second harmonic generation (SHG) crystal as a result of the group velocity mismatch (GVM) in the crystal. A time delay compensator generates an opposite GVM and therefore can be used to improve the overlap of the pulses for the subsequent process (e.g. third harmonic generation, THG in a second nonlinear crystal).
The time delay is adjustable by rotation of the compensator. The specified delay ranges are based on a rotation of ~ +/-12o (external). A larger rotation can be applied for an extended delay range if there is no problem of beam clipping by the edge of the compensator.
Part No. | Description | Material | Wavelength | Delay | Price | Availability | Add to Cart |
Basic Properties of Calcite Crystal:
Transparency Range: 350 - 2300 nm |
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Crystal Symmetry: Trigonal, R3c | ||||
Lattice Constants: a=b=4,994A, c=17,081A | ||||
Density: 2.71 g/cm3 | ||||
Optical Homogeneity: Δn < 10-6/cm | ||||
Mohs Hardness: 3 | ||||
Thermal Expansion Coefficients: | αa = 4.9 x 10-6/K αc = 25.1 x 10-6/K |
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Linear Absorption Coefficients: α<0.01cm-1 from 400 to 700 nm | ||||
Sellmeier Equations: (λ in µm) : |
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Wavelength(nm) | no | ne | Birefringence (Δn=ne-no) |
Walk-off Angle at 45° |
1064 | 1.6423 | 1.4797 | -0.162 | 5.93° |
800 | 1.6487 | 1.4821 | -0.166 | 6.06° |
632.8 | 1.6557 | 1.4852 | -0.171 | 6.18° |
532 | 1.6629 | 1.4886 | -0.174 | 6.30° |
400 | 1.6823 | 1.4974 | -0.185 | 6.61° |
355 | 1.6951 | 1.5032 | -0.192 | 6.82° |
Basic Properties of alpha-BBO Crystal:
Transparency Range: 189 - 3500 nm |
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Crystal Symmetry: Hexagonal R3c | ||||
Lattice Symmetry: a=b=7.2351A,c=39.192A |
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Density: 3.85 g/cm3 | ||||
Thermo-Optic Coefficients: dno/dT= - 9.3 x 10-6 /oC dne/dT= - 1 6 .6 x 10-6/oC |
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Optical Homogeneity: Δn < 10-6/cm | ||||
Mohs Hardness: 4.5 | ||||
Thermal Expansion Coefficients (in the range of 25–900oC) |
αa = 4 x 10-6/K αc = 36 x 10-6/K |
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Linear Absorption Coefficients: α<0.005cm-1 from 300 to 2300 nm | ||||
Sellmeier Equations (λ in µm) : |
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Wavelength(nm) | no | ne | Birefringence (Δn=ne -no) |
Walk-off Angle at 45° |
1550 | 1.6499 | 1.5298 | -0.120 | 4.32° |
1064 | 1.6579 | 1.5380 | -0.120 | 4.29° |
800 | 1.6639 | 1.5432 | -0.121 | 4.30° |
775 | 1.6647 | 1.5438 | -0.121 | 4.30° |
632.8 | 1.6706 | 1.5483 | -0.122 | 4.34° |
532 | 1.6776 | 1.5534 | -0.124 | 4.39° |
400 | 1.6963 | 1.5667 | -0.130 | 4.54° |
355 | 1.7087 | 1.5753 | -0.133 | 4.64° |
266 | 1.7617 | 1.6114 | -0.150 | 5.08° |
Specifications:
Surface Quality: |
20/10 Scratch and Dig |
Optical Axis Orientation: | +/-0.5° |
Parallelism: |
< 15 arc sec |
Flatness: |
λ/4 @ 632.8 nm |
Transmission Wavefront Distortion: |
<λ/4 @ 632.8 nm |
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