GW41 Barium Fluoride (BaF₂) Optical Window
| Origin | Beijing, China |
|---|---|
| Manufacturer Type | Distributor |
| Regional Origin | Domestic (China) |
| Model | GW41 |
| Price Range | USD $0.50 – $299.00 |
| Component Category | Optical Element |
| Available Coatings | UV, VIS, NIR, SWIR Anti-Reflection (AR) |
| Substrate Material | Barium Fluoride (BaF₂) |
| Standard Diameters | 3 mm, 12.5 mm, 12.7 mm, 25.0 mm, 25.4 mm, 40.0 mm, 50.0 mm |
| Standard Thicknesses | 2.0 mm, 3.0 mm |
Overview
The GW41 Barium Fluoride (BaF₂) Optical Window is a precision-engineered transmission optic designed for demanding ultraviolet (UV) to mid-infrared (mid-IR) applications. Constructed from high-purity barium fluoride crystal, this window exhibits exceptional broadband transmittance—from approximately 190 nm in the deep UV through the visible spectrum and into the mid-IR up to ~8.5 µm—making it uniquely suited for spectroscopic, laser delivery, and vacuum-compatible optical systems where wide spectral coverage and low absorption are critical. Unlike fused silica or BK7, BaF₂ maintains usable transmission beyond 7 µm while offering superior UV performance compared to CaF₂ in the sub-200 nm range. Its cubic crystal structure ensures minimal birefringence and excellent wavefront fidelity under normal incidence. The GW41 series is fabricated with tight parallelism (<3 arcsec), surface quality (scratch-dig 20–10 per MIL-PRF-13830B), and λ/10 surface flatness (typ.), enabling integration into interferometric, ellipsometric, and high-resolution imaging setups.
Key Features
- High-transmission BaF₂ substrate with certified bulk homogeneity and low fluorescence under UV excitation
- Standard diameters from 3 mm to 50 mm and thicknesses of 2.0 mm or 3.0 mm—each dimension traceable to NIST-traceable metrology
- Optional broadband anti-reflection coatings optimized for UV (190–400 nm), VIS (400–700 nm), NIR (700–1100 nm), or SWIR (1.1–2.5 µm) spectral bands; coating adhesion validated per MIL-C-48497A
- Chemically stable in dry environments; resistant to thermal shock (thermal expansion coefficient: 18.8 × 10⁻⁶ /°C) and compatible with UHV systems (outgassing rate <1×10⁻¹⁰ Torr·L/s·cm² per ASTM E595)
- Polished to λ/10 surface flatness at 633 nm and surface roughness <5 Å RMS (measured by white-light interferometry)
- Individually serialized and supplied with a certificate of conformance including spectral transmittance data (200–8000 cm⁻¹) and dimensional inspection report
Sample Compatibility & Compliance
The GW41 BaF₂ window is routinely deployed in analytical platforms requiring spectral integrity across multiple domains—including FTIR spectrometers (PerkinElmer, Thermo Fisher Nicolet), UV-VIS-NIR ellipsometers (J.A. Woollam), excimer laser beamlines (ArF, KrF), and synchrotron end-stations. Its material compliance meets ISO 10110-3 (optical element surface form) and ISO 10110-7 (surface imperfections). For regulated environments, the window supports GLP/GMP workflows when paired with documented calibration records and batch-specific material certificates. While BaF₂ is hygroscopic under prolonged ambient humidity >60% RH, all GW41 units are sealed in nitrogen-purged, desiccated packaging with moisture indicator cards; long-term storage above 40% RH is not recommended without protective inert gas purging.
Software & Data Management
No embedded firmware or proprietary software is associated with the GW41 optical window, as it functions as a passive transmission component. However, its performance metrics—including measured transmittance curves, coating reflectance maps, and interferometric flatness profiles—are delivered in standardized formats (CSV, PDF, and Zemax .ZRD-compatible surface error files) for direct import into optical design software (e.g., Zemax OpticStudio, CODE V, FRED). Spectral data conforms to ASTM E275 and ISO/DIS 9050 for optical coating characterization. Traceability documentation includes lot-specific refractive index values (nd = 1.473 @ 589.3 nm, nF = 1.487, nC = 1.468) and Abbe number (νd ≈ 52.3), enabling accurate modeling in multi-wavelength system simulations.
Applications
- UV photolithography mask inspection windows and excimer laser (193 nm, 248 nm) beam delivery optics
- FTIR sample compartment windows and ATR crystal coupling interfaces
- Vacuum chamber viewports for plasma diagnostics and molecular beam experiments
- Beam splitters and cavity mirrors in tunable OPO and QCL systems operating between 2–7 µm
- Reference optics in radiometric calibration chains traceable to NIST SRM 2065 (spectral irradiance standards)
- Space-qualified sensor protection elements in Earth observation payloads (compatible with ECSS-Q-ST-70-02C outgassing requirements)
FAQ
Is BaF₂ suitable for use in high-humidity environments?
No—barium fluoride is moderately hygroscopic. Prolonged exposure to relative humidity >60% may cause surface clouding or etching. Use in controlled dry air or nitrogen-purged enclosures is strongly advised.
Can GW41 windows be custom-coated for dual-band AR performance (e.g., UV + MWIR)?
Yes. Custom multi-band coatings (e.g., 190–400 nm + 3–5 µm) are available upon request; lead time extends by 3–4 weeks and requires spectral specification and environmental durability requirements.
What is the maximum continuous-wave laser power density the GW41 window can withstand?
At 1064 nm with AR coating, damage threshold exceeds 10 J/cm² for 10 ns pulses (10 Hz); for CW operation, thermal lensing becomes limiting above 5 kW/cm²—consult application engineering for heat-sink mounting recommendations.
Are dimensional tolerances held to ISO 2768-mK or tighter?
Standard tolerances are ±0.05 mm on diameter and ±0.1 mm on thickness. Tighter tolerances (±0.01 mm) are available under custom order with additional metrology validation.
Does the GW41 series comply with RoHS or REACH regulations?
Yes—material composition and manufacturing processes conform to EU Directive 2011/65/EU (RoHS 2) and Regulation (EC) No 1907/2006 (REACH), with full SVHC declaration available upon request.
