Collection: 1064nm Bandpass Filter

1064nm Filter Selection Guide for Targeted Applications

I. Filter Configuration for Laser Processing Systems

Application Scenario

In Nd:YAG laser cutting/welding equipment, precise control over the laser optical path and operator safety protection are critical requirements.

Filter Specification Requirements

1. Spectral Characteristics

• Central Wavelength: 1064nm ± 0.5nm (ensures precise matching with the laser source)
• Bandwidth: ≤8nm (narrow-bandpass design to suppress harmonic interference like 532nm frequency-doubled light)
• Reflectivity: >99% @ 1064nm (high-reflectivity negative filter)
• Blocking Depth: OD≥6 @ 400-1100nm (effectively blocks visible and infrared stray light)

2. Optical Performance

• Laser Damage Threshold: >15J/cm² (pulsed laser) or >300mW (continuous wave, matched to laser power density)
• Surface Quality: MIL-spec 40-20 (reduces energy loss from scattering)

3. Material and Structure

• Substrate Material: Fused silica or CaF₂ (high laser damage threshold, low absorption characteristics)
• Coating Design: SiO₂/TiO₂ multi-layer dielectric film (over 100 layers), deposited via Ion Beam Assisted Deposition (IAD) to enhance film density
• Anti-Reflective Coating: Broadband AR coating on both sides (average reflectivity <0.2% @ 400-1600nm, minimizing optical path loss)

Selection Logic and Problem Solving

• High Reflectivity Design: Utilizes Fabry-Perot interference to create a strong reflection peak at 1064nm, confining laser energy within the optical path to avoid processing inaccuracies from diffuse reflection.
• Narrow Bandpass Features: Suppresses frequency-doubled light (e.g., 532nm) and ambient light interference, preventing sensor misactivation or optical component damage.
• High Damage Threshold: Hard coating processes (e.g., ion beam sputtering) enable the filter to withstand megawatt-level laser power, avoiding system failures from coating rupture.
• Material Selection: CaF₂ substrate offers >95% transmittance at 1064nm and high thermal conductivity (9.71W/m·K), suitable for long-term high-power laser environments.

II. Filter Configuration for LiDAR Systems

Application Scenario

In automotive LiDAR systems, efficient transmission of 1064nm laser signals and suppression of background noise are essential.

Filter Specification Requirements

1. Spectral Characteristics

• Central Wavelength: 1064nm ± 1nm (matches the response peak of InGaAs detectors)
• Bandwidth: 2-8nm (narrower bandwidth enhances anti-interference capability based on system SNR requirements)
• Transmittance: >95% @ 1064nm (ensures signal strength)
• Blocking Characteristics: T<0.1% @ 800-1000nm & 1100-1600nm (suppresses sunlight and other laser interference)

2. Optical Performance

• Insertion Loss: <0.8dB (minimizes signal attenuation)
• Polarization-Dependent Loss (PDL): <0.1dB (ensures signal integrity)
• Temperature Stability: Δλ/ΔT ≤0.005nm/℃ (operates reliably in -40℃ to +85℃ environments)

3. Material and Structure

• Substrate Material: BK7 glass or silicon single crystal (balances cost and infrared transmittance)
• Coating Design: Ta₂O₅/SiO₂ multi-layer film, deposited via magnetron sputtering for nanometer-level thickness control
• Dimensional Accuracy: Diameter tolerance ±0.05mm, parallelism <1 arcminute (compatible with fiber coupling systems)

Selection Logic and Problem Solving

• Narrow Bandpass Design: Precise control of film thickness (error <1nm) allows only 1064nm laser transmission, suppressing near-infrared ambient light (e.g., 850nm/940nm) and improving SNR.
• High Transmittance: Ion Beam Assisted Deposition (IBAD) optimizes refractive index matching, achieving >95% transmittance at 1064nm to ensure effective detection of long-range echo signals.
• Temperature Stability: Gradient film design compensates for thermal wavelength shifts, eliminating system misjudgment caused by environmental temperature changes.
• Low Insertion Loss: Double-sided AR coatings reduce interface reflection (R<0.2%), extending LiDAR detection range (e.g., from 200m to 300m).

III. Key Selection Criteria Comparison

• Core Trade-offs:
• Laser Processing: High-power laser protection vs optical path efficiency
• LiDAR: Signal strength vs environmental noise suppression
• Spectral Characteristics:
• Laser Processing: High reflectivity (>99%)
• LiDAR: High transmittance (>95%)
• Damage Threshold:
• Laser Processing: >15J/cm² (pulsed)
• LiDAR: >300mW (continuous wave)
• Material Choice:
• Laser Processing: CaF₂ (for high damage resistance)
• LiDAR: BK7 glass (cost-effective solution)
• Process Priorities:
• Laser Processing: Hard coatings (for protection against laser impacts)
• LiDAR: Precision thickness control (nanometer-level)

IV. Environmental Adaptation Design Recommendations

1. High-Temperature Environments (e.g., Industrial Furnaces)

• Use fused silica substrate (thermal expansion coefficient 5.5×10⁻⁷/℃) with metal-dielectric composite films (e.g., Cr/SiO₂ layers), capable of withstanding 300℃.
• Avoid organic adhesives; use metal compression rings for mounting to prevent thermal delamination.

2. High-Humidity Environments (e.g., Outdoor LiDAR)

• Apply hard coatings (hardness >8H) that pass 1000-hour 85℃/85%RH reliability testing.
• Coat substrate edges with hydrophobic materials (e.g., Teflon) to prevent moisture ingress at film interfaces.

3. Vibration-Prone Environments (e.g., Automotive Platforms)

• Select silicon single crystal substrate (fracture strength 2.8GPa) with optimized coating stress (residual stress <0.3GPa) to prevent vibration-induced cracking.
• Use elastic mounts to reduce mechanical stress transfer.

Conclusion

Selecting 1064nm filters requires prioritizing application-specific core challenges: high-power protection and optical purity for laser processing, versus signal integrity and environmental robustness for LiDAR. By integrating spectral characteristics, material selection, and process optimization, this approach achieves an optimal balance between system performance and cost efficiency.