コレクション: 10000nm バンドパスフィルター

10000nm (10μm) Filter Application Selection Guide

I. Filter Configuration for Industrial Thermal Imaging Systems

In industrial equipment fault prediction and energy efficiency monitoring, long-wave infrared (LWIR) thermal imaging systems require precise capture of thermal radiation signals in the 8–14μm band. Key filter requirements for this application include:

1. Spectral Characteristics

• Bandpass Range: Strictly limited to 8–14μm to cover the peak region of blackbody radiation. For example, a filter using a silicon (Si) substrate with multilayer Ge/SiO₂ dielectric coatings can achieve high transmittance (T>70%) in 9–13μm, with out-of-band rejection (T<1%) across UV–20μm.
• Anti-Interference Design: Integrates notch filters to suppress visible (400–700nm) and near-infrared (700–2500nm) interference, preventing detector saturation. Metal coating layers on germanium (Ge) substrates achieve OD3-level out-of-band suppression.

1. Material and Process

• Substrate Selection: Germanium single crystal (Ge) is preferred for its high transmittance (>90% in 8–14μm) and excellent mechanical/thermal conductivity, suitable for high-temperature environments. Cost-sensitive applications may use silicon (Si), requiring anti-reflective coatings to compensate for absorption losses near 10μm.
• Coating Technology: Ion Beam Sputtering (IBS) deposits multilayer dielectric films with packing density >0.95, reducing moisture-induced wavelength drift (<1nm/℃). Diamond-like carbon (DLC) hard coatings (hardness >10GPa) protect against oil/dust abrasion.

1. Selection Rationale

• Background Noise Elimination: 8–14μm bandpass design avoids water vapor absorption peaks (e.g., 6.3μm) outside atmospheric windows, reducing environmental interference.
• SNR Enhancement: High Ge transmittance combined with narrow bandpass (FWHM≈4μm) increases detected thermal signal strength by over 30%.
• Environmental Adaptability: DLC coatings and sealed structures ensure stability from -40℃ to 85℃, meeting outdoor industrial requirements.

II. Filter Configuration for Methane Leak Detection

In petrochemical pipeline monitoring and environmental safety, methane (CH₄) exhibits a strong absorption peak at 7.66μm. Key filter requirements for this application include:

1. Spectral Characteristics

• Center Wavelength Precision: Requires precise matching to the methane absorption peak (7.669μm±0.02μm). "Split-layer" coating design with electron beam evaporation achieves wavelength error <0.3%.
• Narrow Bandpass Design: Full Width at Half Maximum (FWHM) controlled between 59–120nm. For example, a sapphire (Al₂O₃) substrate with Ge/SiO₂ coatings provides 7.66μm center wavelength and 120nm bandwidth, with out-of-band rejection (T<0.5%) across 400–12,000nm.

1. Material and Process

• Substrate Selection: Sapphire (Al₂O₃) is preferred for high-temperature environments due to low thermal expansion (7.5×10⁻⁶/℃) and mechanical strength. Zinc selenide (ZnSe) offers higher transmittance but requires moisture resistance considerations.
• Coating Technology: Ion-Assisted Deposition (IAD) controls film stress within ±50MPa, minimizing temperature-induced wavelength drift (<0.05nm/℃).

1. Selection Rationale

• Selective Absorption: Narrow bandpass design excludes interference from CO₂ (4.26μm) and H₂O (6.3μm), enabling ppm-level methane detection sensitivity.
• SNR Enhancement: Optimized λ/4 stack coatings achieve peak transmittance >85% and OD3-level stray light suppression, doubling detector SNR.
• Dynamic Tunability: Graphene-based tunable filters in portable devices allow ±50nm spectral tuning via electrostatic gating, adapting to varying methane concentrations.

III. Key Parameter Comparison for Selection

• Center Wavelength
• Industrial Thermal Imaging: 8–14μm (broadband, covering blackbody radiation peak)
• Methane Detection: 7.66μm (narrowband, matching methane molecular vibration absorption)
• Substrate Material
• Industrial Thermal Imaging: Germanium (Ge, high transmittance >90% in 8–14μm); Silicon (Si, cost-effective with anti-reflective compensation for 10μm absorption)
• Methane Detection: Sapphire (Al₂O₃, high-temperature resistance with low thermal expansion); Zinc Selenide (ZnSe, high transmittance but requires moisture protection)
• Coating Process
• Industrial Thermal Imaging: Ion Beam Sputtering (IBS), packing density >0.95, wavelength drift <1nm/℃
• Methane Detection: Electron Beam Evaporation + Ion-Assisted Deposition (EAD-IAD), stress control ±50MPa, wavelength drift <0.05nm/℃
• Out-of-Band Rejection
• Industrial Thermal Imaging: UV–20μm, T<1% (OD3-level suppression of visible/NIR interference)
• Methane Detection: 400–12,000nm, T<0.5% (excluding CO₂/H₂O absorption peaks)
• Temperature Stability
• Industrial Thermal Imaging: Operating range -40℃ to 85℃, wavelength drift <1nm/℃ (suitable for outdoor high-temperature monitoring)
• Methane Detection: Operating range -20℃ to 60℃, wavelength drift <0.05nm/℃ (meeting portable device environmental requirements)
• Typical Applications
• Industrial Thermal Imaging: High-temperature equipment monitoring, power system efficiency analysis, industrial furnace thermal mapping
• Methane Detection: Petrochemical pipeline leak inspection, landfill gas monitoring, coal mine gas concentration warning

IV. Selection Decision

1. Determine Target Wavelength Band

• Broadband (8–14μm) for general thermal radiation capture; Narrowband (e.g., 7.66μm) for specific gas absorption matching.

1. Evaluate Environmental Conditions

• High-temperature: Prioritize Ge substrates with DLC coatings; Moist environments: Avoid ZnSe, opt for sapphire or silicon substrates.

1. Balance Performance and Cost

• High-end applications (e.g., aerospace): Ge substrate + IBS coatings; Industrial applications: Si substrate + electron beam evaporation for cost reduction.

1. Validate Anti-Interference Capability

• Confirm out-of-band rejection (e.g., OD3-level) via spectral testing; Test background noise suppression in real-world scenarios.

These configurations enable filters to accurately extract target signals, solving background interference in thermal imaging and low-concentration identification in gas detection, ultimately enhancing system reliability and sensitivity.