Key Features
- Broad transparency across infrared (IR), visible, and ultraviolet (UV) spectrums.
- High thermal and mechanical stability, suitable for demanding environments.
- Superior resistance to chemical corrosion and degradation.
- Precise optical homogeneity, ensuring minimal wavefront distortion.
- Customizable coatings for enhanced spectral performance.
General Description
Infrared crystals are essential for advanced photonics applications, offering exceptional optical properties across IR, UV, and visible wavelengths. Common materials like BaF₂, CaF₂, MgF₂, and LiF exhibit low absorption losses and high transparency. These crystals are characterized by their high thermal conductivity, low refractive indices, and resistance to environmental stressors. Each material, whether natural or synthetic, is optimized for specific uses, including laser systems, spectrometry, and thermal imaging.
General Applications and Examples
- BaF₂ Crystal: Widely used in thermal imaging, spectrometers, and radiation detectors due to its broad IR transmission range.
- CaF₂ Crystal: Essential for high-precision optics like lenses and windows in spectroscopy and astronomy.
- MgF₂ Crystal: Common in antireflective coatings and optical windows for ultraviolet and visible spectrums.
- LiF Crystal: Ideal for UV laser systems and cryogenically cooled environments.
- ZnSe Crystal: A staple in IR laser optics, thermal imaging systems, and medical devices.
- ZnS Crystal: Used in multispectral applications including night vision and IR sensors.
- Silicon Crystal: Integral for mid-IR systems and Fourier-transform infrared (FTIR) spectrometry.
- Germanium Crystal: Preferred for thermal imaging systems and IR lenses due to high refractive indices.
- Quartz Crystal: Suited for wave retarders, polarizers, and high-stability frequency control devices.
- Sapphire Crystal: Known for its exceptional hardness and wide spectral range, used in harsh conditions like aerospace and medical systems.
Comparison of Crystals
| Crystal | Density (g/cm³) | Thermal Conductivity (W/m·K) | Refractive Index (λ) | Transmission Range (µm) | Hardness |
|---|---|---|---|---|---|
| BaF₂ | 4.89 | 9.2 | 1.48 (0.55 µm) | 0.15–12 | 82 |
| CaF₂ | 3.18 | 9.7 | 1.43 (0.55 µm) | 0.13–10 | 158 |
| MgF₂ | 3.18 | 21.3 | 1.38 (0.55 µm) | 0.11–8 | 6.0 (Mohs) |
| LiF | 2.64 | 14.0 | 1.39 (0.55 µm) | 0.11–7 | 4.0 (Mohs) |
| ZnSe | 5.27 | 18.0 | 2.40 (0.55 µm) | 0.6–20 | 120 |
| ZnS | 4.09 | 27.0 | 2.35 (0.55 µm) | 0.4–12 | 120 |
| Silicon | 2.33 | 149 | 3.42 (3.4 µm) | 1.2–8 | 7.0 (Mohs) |
| Germanium | 5.33 | 60 | 4.00 (3.5 µm) | 1.8–15 | 6.0 (Mohs) |
| Quartz | 2.64 | 10.7 | 1.54 (0.55 µm) | 0.18–3.5 | 7.0 (Mohs) |
| Sapphire | 3.97 | 25.1 | 1.76 (0.55 µm) | 0.15–5.5 | 9.0 (Mohs) |
Standard Fabrication Specifications
| Specification | Value |
|---|---|
| Surface Quality | 10/5 to 40/20 scratch-dig rating |
| Thickness Tolerance | ± 0.1 mm |
| Flatness | λ/10 at 633 nm |
| Parallelism | < 10 arc seconds |
| Coating Options | AR coatings (UV-IR) |