GW91 Germanium (Ge) Optical Window
| Origin | Beijing, China |
|---|---|
| Manufacturer Type | Distributor |
| Origin Category | Domestic |
| Model | GW91 |
| Price Range | USD 72–143 (based on size and configuration) |
| Component Category | Optical Element |
| Diameter | 3–50 mm |
| Thickness | 1.0–3.0 mm |
| Coating | Dual-Side Broadband Anti-Reflection (BBAR), Ravg < 1% @ 8–12 µm |
| Substrate Material | Single-Crystal Germanium (Ge) |
| Uncoated Transmission Curve Reference | 5 mm thick Ge sample |
| Compliance | ISO 10110-1 optical surface specifications (scratch-dig per customer request) |
Overview
The GW91 Germanium (Ge) Optical Window is a precision-engineered infrared (IR) transmissive component designed for demanding mid-wave to long-wave infrared (MWIR/LWIR) applications spanning 8–12 µm. Fabricated from high-purity, single-crystal germanium, the GW91 window leverages the intrinsic high refractive index (~4.0 at 10 µm) and exceptional transmission characteristics of Ge in the thermal IR band—where conventional optical glasses and fused silica are opaque. Unlike silicon or zinc selenide, germanium offers superior thermal conductivity (60 W/m·K) and mechanical rigidity, enabling stable performance under moderate thermal load and vacuum environments typical of FTIR spectrometers, thermal imaging systems, CO₂ laser cavities, and industrial process monitoring sensors. The window operates on the principle of broadband transmittance through a low-absorption semiconductor substrate, with transmission efficiency governed by Fresnel reflection losses and bulk absorption—both minimized via precise crystal orientation (typically ⟨100⟩), controlled dopant levels (<1×10¹⁵ cm⁻³), and optimized AR coating design.
Key Features
- Single-crystal germanium substrate conforming to ASTM F1314 specifications for IR optical grade material
- Dual-side broadband anti-reflection (BBAR) coating engineered for Ravg < 1.0% across 8–12 µm—validated via spectral reflectance measurement per ISO 9050
- Standard thickness tolerance: ±0.05 mm; diameter tolerance: ±0.1 mm; surface flatness λ/4 @ 633 nm (per ISO 10110-3)
- Optional surface quality options available: 20–10 scratch-dig (MIL-PRF-13830B) or tighter upon request
- Thermal expansion coefficient: 6.1 × 10⁻⁶ /°C (20–100 °C), compatible with aluminum, stainless steel, and Kovar mounting interfaces
- No internal stress birefringence detectable under crossed polarizers (≤5 nm/cm retardation)
Sample Compatibility & Compliance
The GW91 window is compatible with standard kinematic mounts, O-ring sealed housings, and vacuum flanges (CF, KF, or ISO-K). Its germanium substrate meets RoHS Directive 2011/65/EU restrictions on hazardous substances and is fully traceable to raw material lot certification. All coated variants undergo environmental durability testing per MIL-C-48497A (adhesion, humidity, abrasion) and are suitable for Class 1000 cleanroom handling. While not intrinsically certified for medical or aerospace use, the component satisfies baseline requirements for ISO 9001-compliant optical assembly processes and supports full documentation packages—including coating spectral data reports, interferometric surface maps, and material certificate of conformance (CoC).
Software & Data Management
As a passive optical component, the GW91 requires no embedded firmware or driver software. However, its spectral performance data (transmission vs. wavelength, reflectance curves, and angle-of-incidence sensitivity) are provided in standardized ASCII format (.txt) and CSV-compatible files, fully importable into optical design platforms such as Zemax OpticStudio, CODE V, and FRED. Customers receive a digital calibration report including measured transmission spectra (PerkinElmer Lambda 950 or equivalent FTIR spectrometer), surface figure error (Zygo GPI interferometer), and coating uniformity analysis. All datasets adhere to FAIR principles (Findable, Accessible, Interoperable, Reusable) and may be integrated into enterprise PLM or LIMS systems via API-accessible metadata tagging.
Applications
- Front-end protective windows for uncooled microbolometer arrays in LWIR thermal cameras
- Output couplers and cavity end mirrors in sealed CO₂ laser systems (10.6 µm)
- Sample compartment windows in Fourier-transform infrared (FTIR) spectrometers operating in the fingerprint region
- Sensing elements in gas analyzers targeting hydrocarbons, SF₆, and refrigerants with absorption bands between 8–12 µm
- Vacuum-compatible viewports for in-situ IR process monitoring in semiconductor CVD and plasma etch tools
- Calibration reference windows in radiometric test benches compliant with NIST-traceable protocols
FAQ
Is the GW91 window suitable for high-vacuum applications?
Yes—germanium exhibits negligible outgassing (water vapor desorption rate < 1×10⁻⁹ Torr·L/s·cm² per ASTM E595) and maintains structural integrity under ≤10⁻⁷ Torr conditions when properly mounted.
Can I specify custom AR coating bands beyond 8–12 µm?
Yes—custom BBAR coatings covering 3–5 µm (MWIR) or dual-band designs (e.g., 3–5 µm + 8–12 µm) are available with lead times of 4–6 weeks.
What is the maximum operating temperature for sustained use?
Continuous operation up to 70 °C is recommended; short-term exposure to 100 °C is permissible if thermal gradients remain below 5 °C/mm.
Do you provide mounting hardware or cell assemblies?
Standard anodized aluminum retaining rings and compression gaskets are offered as optional accessories; custom-machined mounts comply with IPC-A-610 Class 2 standards.
Is there batch-to-batch variation in transmission performance?
No—material sourcing is restricted to two qualified Ge ingot suppliers, and every production lot undergoes full spectral validation; transmission deviation across batches is maintained within ±0.3% absolute over 8–12 µm.
