280nm Bandpass Filter

Belonging to the ultraviolet C (UVC) spectrum, 280nm light exhibits high photon energy, enabling effective disruption of microbial DNA/RNA structures, while also demonstrating selective excitation capability for specific fluorescent molecules.

  • Application 1: UV Sterilization Systems - Deployed in UV disinfection equipment to precisely isolate the 280nm wavelength, it achieves efficient inactivation of bacteria, viruses, and other pathogens in air or water systems, ensuring hygiene standards in critical environments such as healthcare facilities and food processing plants.
  • Application 2: Biomolecular Analysis - Utilized in analytical instruments like fluorescence spectrophotometers, the 280nm bandpass filter selectively transmits this wavelength to facilitate accurate measurement of protein/nucleic acid fluorescence excitation or absorption spectra, supporting applications in biochemistry, molecular biology, and medical diagnostics.
  • Application 3: Semiconductor Quality Control - In research and industrial inspection, this filter enables non-destructive detection of sub-micron defects on semiconductor wafer surfaces by leveraging the unique penetration properties of 280nm light and its wavelength-specific selectivity, critical for advanced microelectronics manufacturing.

280nm Optical Filter Selection Guide for Specific Applications

I. Filter Configuration for UVC Sterilization Systems

Application Scenarios: Air/water disinfection equipment, medical instrument sterilizationFilter Requirements:

1. Bandpass Filter (Center Wavelength 280nm, FWHM 10-12nm)

  • Core Parameters:
  • Transmission Range: 270-290nm (covers the effective sterilization band of 280nm±10nm)
  • Cutoff Depth: OD4+ (blocking rate >99.99%, achieving high cutoff across 200-1100nm full spectrum)
  • Substrate & Coating: Fused silica substrate with ion-beam sputtered hard coatings (UV resistance >10,000 hours)
  • Selection Rationale:
  • Narrow bandwidth eliminates stray light interference from 254nm mercury lamps (prevents false activation of human safety mechanisms)
  • Deep cutoff prevents visible light leakage, protecting operator eyes (UVC band causes severe damage to human skin/cornea)
  • Hard coating technology resists film degradation from long-term UV irradiation (common resin filters yellow and fail under UVC)

2. Auxiliary Shortpass Filter (Cutoff Wavelength 300nm)

  • Configuration: Cascaded with the bandpass filter
  • Function: Further blocks near-UV/visible light above 300nm, limiting system light leakage to <0.01%
  • Technical Advantage: Steepness >50nm/OD (narrow transition band for high spectral purity)

Key Problems Addressed:

  • Balancing Efficiency and Safety: Precise 280nm transmission ensures sterilization efficiency (optimal for DNA pyrimidine dimer disruption), while dual cutoff design avoids stray light hazards
  • Extended Equipment Lifespan: Hard-coated structure reduces UV-induced attenuation to <5% annually, minimizing maintenance costs

II. Filter Combination for Time-Resolved Fluorescence Detection

Application Scenarios: Biomarker detection (e.g., serum protein quantification), rapid food safety screeningFilter Configuration:

1. Excitation Side: 280nm Bandpass Filter

  • Critical Parameters:
  • FWHM: 8-10nm (matches the excitation spectrum half-peak width of target fluorophores)
  • Transmittance: >65% (in 270-290nm range to ensure sufficient excitation intensity)
  • Stray Light Suppression: OD6@254nm (eliminates residual mercury lamp spectral lines)
  • Design Considerations:
  • Multilayer coating system (20+ alternating high/low refractive index layers) for compatible narrow bandpass and deep cutoff
  • Fused silica substrate (transmittance >90% at 280nm, superior to common glass)

2. Emission Side: 320nm Longpass Filter + Notch Filter Combination

  • First Stage: 320nm Longpass Filter (Cutoff Depth OD4@300nm)
  • Function: Separates fluorescence emission signals (320-350nm target range) while blocking residual excitation light
  • Second Stage: 280nm Notch Filter (Suppression Depth OD6)
  • Role: Eliminates residual excitation light to enhance signal-to-noise ratio (S/N >100:1)

Selection Logic:

  • Spectral Matching: Excitation filter bandwidth covers the fluorophore's excitation peak (e.g., tryptophan absorption peak at 280nm); emission filter cutoff wavelength lies below the fluorescence emission start (320nm)
  • Time-Resolved Performance: Notch filter limits excitation light leakage to <0.001%, enabling detection of long-lifetime fluorescence signals (lanthanide fluorescence lifetime 10-100μs) after background fluorescence decay (10-20ns)

Technical Value:

  • Enables ultra-trace detection (detection limit down to pg/mL), 100x higher sensitivity than conventional fluorescence methods
  • Enhanced anti-interference capability for direct detection in complex matrices (e.g., whole blood samples) without tedious pretreatment

III. Key Selection Parameter Comparison

For UVC Sterilization Applications

  • Filter Type: Bandpass + Shortpass combination
  • Center Wavelength: 280nm
  • FWHM: 10-12nm
  • Cutoff Depth: OD4-6
  • Material/Process: Fused silica substrate + ion-beam sputtered hard coatings

For Fluorescence Detection Applications

  • Filter Type: Bandpass + Longpass + Notch combination
  • Center Wavelength: 280nm (excitation side)/320nm (emission side)
  • FWHM: 8-10nm (excitation side)
  • Cutoff Depth: OD6 (notch filter)
  • Material/Process: Fused silica substrate + ion-assisted deposition process

Important Considerations:

  1. Avoid common glass substrates (transmittance <30% at 280nm)
  2. For high-power UVC applications (e.g., industrial sterilization), select substrates with thermal conductivity >1W/m·K (e.g., sapphire)
  3. Perform angle response testing for fluorescence detection systems (incidence angle deviation >5° may cause spectral shift)

This configuration ensures system performance while controlling filter costs within 15-20% of total equipment budget (depending on coating layers and material selection).

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