370nm Bandpass Filter

Occupying the near-ultraviolet spectral region, this wavelength possesses specific photon energy to excite fluorescence in luminescent materials while enabling penetration through certain transparent media.

  • Application 1: In fluorescence microscopy, it selectively transmits 370nm excitation light to activate fluorescent markers in samples, effectively minimizing stray light interference for clearer imaging.
  • Application 2: Integrated into environmental monitoring devices, the filter works with sensors to precisely capture 370nm ultraviolet absorption signals, facilitating quantitative analysis of target gases like ozone precursors.
  • Application 3: Serving as a core component in biological detection kits, it eliminates background light noise to ensure efficient excitation of fluorescent probes by 370nm light, significantly enhancing the sensitivity of nucleic acid or protein assays.

370nm Filter Selection Guide: Configuration Analysis for Typical Applications

I. Fluorescence Detection Systems (e.g., Sulfur Dioxide/Bisulfite Ratiometric Fluorescent Probe Detection)

In fluorescence detection, 370nm is commonly used as the excitation wavelength for activating specific fluorescent markers. Take the sulfur dioxide detection probe developed by Jinan University as an example, which has an excitation wavelength of 370nm and detection wavelengths of 425nm and 635nm. To achieve precise separation of fluorescent signals, the following filter configurations are required:

1. Excitation Filter

  • Central Wavelength: 370nm
  • Bandwidth: 10–36nm (e.g., FF01-370/10-25 or FF01-370/36-25)
  • Cutoff Characteristics: OD6 (Optical Density ≥6), effectively blocking stray light in 250–340nm and 394–800nm bands
  • Substrate Material: Fused silica, ensuring high transmittance (>85%) in the deep ultraviolet region
Selection Rationale

The narrow-bandpass design accurately filters 370nm excitation light to avoid interference from other wavelengths. The deep cutoff characteristic (OD6) suppresses background noise, significantly improving the signal-to-noise ratio. For instance, an excessively wide bandwidth (>50nm) may introduce visible light contamination, reducing detection sensitivity.

2. Dichroic Mirror

  • Reflection Band: 370nm (±5nm)
  • Transmission Band: 400–800nm
  • Incidence Angle Design: Optimized for 45° incidence to efficiently separate reflected excitation light and transmitted emission light
Selection Rationale

Coating technology enables high reflection (>90%) for the excitation wavelength and high transmission (>85%) for longer wavelengths, directing excitation light to the sample while preventing it from entering the detector and interfering with fluorescent signals.

3. Emission Filters

  • Dual-Band Configuration:

- 425nm bandpass (50nm bandwidth, e.g., FF01-425/50-25)

- 635nm bandpass (50nm bandwidth, e.g., FF01-635/50-25)

  • Cutoff Characteristics: OD6 to block excitation light and non-target emission light
Selection Rationale

Targeting the probe's dual emission peaks (425nm and 635nm), the dual-bandpass filters simultaneously collect ratiometric signals, eliminating the effects of light source fluctuations and sample concentration variations to improve detection accuracy.

II. Semiconductor Lithography Processes (e.g., Micro-LED UV Exposure)

In semiconductor microfabrication, 370nm UV light is used for selective exposure of photoresist. Taking the gallium nitride micro-LED lithography system as an example, the filter configuration must meet the following requirements:

1. Narrow-Bandpass Filter

  • Central Wavelength: 370nm
  • Bandwidth: ≤2nm (e.g., FF01-370/2-25)
  • Transmittance: >90% (fused silica substrate with hard coating technology)
  • Damage Threshold: >5J/cm², resistant to high-power UV lasers (3.0mW/cm² continuous irradiation)
Selection Rationale:

The ultra-narrow bandwidth ensures wavelength consistency for photoresist exposure, preventing pattern deformation caused by wavelength drift. High-damage-threshold materials (e.g., CaF₂) withstand prolonged high-energy UV irradiation, extending filter service life.

2. Long-Pass Filter

  • Cutoff Wavelength: 380nm
  • Transmission Band: 380–800nm
  • Cutoff Depth: OD4 (blocks 370nm excitation light)
Selection Rationale:

Used in post-lithography inspection to filter residual 370nm excitation light, allowing only photoresist fluorescence signals (e.g., 400–500nm) to pass through and ensuring imaging clarity.

III. Core Selection Logic and Problem Solving

1. Interference Suppression in Fluorescence Detection

  • Background Noise Control: The deep cutoff characteristic (OD6) of the excitation filter suppresses stray light to below 0.001%, addressing the issue of fluorescent signals being overwhelmed by ambient light or device self-emission.
  • Ratiometric Detection Advantage: Dual emission filters use signal ratios to eliminate light source fluctuations. For example, the 425nm/635nm signal ratio in sulfur dioxide detection reduces measurement error to within ±2%.

2. Precision Assurance in Lithography Processes

  • Wavelength Stability: The narrow-bandpass filter (bandwidth ≤2nm) controls exposure wavelength fluctuations within ±1nm, ensuring consistent photoresist reactions and avoiding nanometer-scale pattern deviations.
  • Material Durability: Fused silica substrates with UV resistance (service life >10,000 hours) reduce risks of process yield decline due to filter performance degradation.

3. Cross-Application Adaptability

  • Balancing Fluorescence Detection and Lithography: The bandwidth selection for 370nm excitation filters balances light intensity and monochromaticity—wider bandwidths (e.g., 36nm) are acceptable for fluorescence detection to improve excitation efficiency, while ultra-narrow bandwidths (2nm) are necessary for lithography to ensure resolution.

Through these configurations, 370nm filters enable highly sensitive analysis in fluorescence detection and ensure nanometer-scale pattern precision in lithography. Optimizations in material and coating technologies further meet stability and durability requirements across different applications.

Message us