450nm Bandpass Filter

As part of the blue light spectrum, 450nm light features high photon energy, a narrow wavelength bandwidth, and specific positioning within the visible spectrum, making it ideal for optical systems requiring precise wavelength control.

  • Application 1:  (Fluorescence Imaging) In fluorescence imaging systems, the 450nm bandpass filter blocks stray light and transmits only 450nm excitation light, efficiently activating blue-responsive fluorescent markers (e.g., FITC derivatives) in samples to enhance imaging contrast and specificity.
  • Application 2:  (Environmental Monitoring) Used in environmental monitoring devices, this filter isolates 450nm characteristic absorption signals from water or gas samples to accurately detect pollutants with conjugated double-bond structures (such as polycyclic aromatic hydrocarbons, PAHs), enabling quantitative analysis of trace substances.
  • Application 3:  (LED Production Quality Control) Paired with spectrometers in LED manufacturing, the 450nm bandpass filter eliminates non-target wavelength noise, allowing precise measurement of blue LED chip parameters including peak wavelength, full width at half maximum (FWHM), and light intensity distribution to ensure compliance with wavelength accuracy standards for lighting and display devices.

450nm Filter Selection Guide (Application-Oriented)

1. Configuration for Excitation and Emission Paths in Fluorescence Microscopy

In fluorescence imaging, 450nm filters play a critical role. Take blue-excited fluorescent dyes (such as FITC, GFP) as an example—their excitation spectrum peaks typically at 485–495nm, requiring an excitation filter to selectively transmit this wavelength band. Typical specifications include:

  • Central Wavelength: 450±2nm (covering the main peak of blue LEDs or mercury lamps)
  • Full Width at Half Maximum (FWHM): 10–20nm (narrow-band design to minimize stray light interference)
  • Passband Transmission: ≥95% (ensuring sufficient excitation energy)
  • Stopband Optical Density: OD≥4 (effectively suppressing long waves above 500nm to avoid background contamination)

For the emission filter matching the dye's fluorescence spectrum (e.g., 520–530nm), the configuration should be:

  • Central Wavelength: 520±5nm
  • Full Width at Half Maximum: 30–50nm (wider bandwidth to capture complete fluorescence signals)
  • Cutoff Range: 200–480nm (completely blocking residual excitation light)
  • Transition Bandwidth: ≤20nm (steep cutoff characteristics to enhance signal-to-noise ratio)

Selection Rationale:

  • The narrow bandwidth of the excitation filter (e.g., 10nm) precisely isolates the blue excitation light, preventing adjacent wavelengths (such as UV or green light) from mistakenly triggering fluorescence signals. For instance, a filter with excessive bandwidth may allow nearby wavelengths to enter the optical path, causing false-positive signals.
  • The high cutoff depth (OD≥6) of the emission filter effectively isolates excitation light. Even if excitation energy leaks, the deep cutoff attenuates it below the detection threshold. In confocal microscopy, this design significantly reduces cross-talk interference and improves image contrast.

2. Wavelength Sorting and Testing for Blue LEDs

In the quality control of LED production, 450nm filters are used to screen wavelength consistency. Typical specifications include:

  • Central Wavelength: 450±1nm (precisely matching the nominal wavelength of blue LEDs)
  • Full Width at Half Maximum: 5–8nm (ultra-narrow-band design to distinguish adjacent wavelength models)
  • Peak Transmission: ≥90% (high transmission for sensitive detection)
  • Cutoff Range: 380–445nm & 455–550nm (dual-band cutoff to exclude UV and green light interference)
  • Damage Threshold: ≥500mW/cm² (suitable for high-power testing light sources)

Selection Rationale:

  • The ultra-narrow bandwidth (e.g., 5nm) controls wavelength deviation within ±2nm, meeting the strict requirements of high-end LEDs (such as medical-grade). A filter with wider bandwidth (e.g., 20nm) might misclassify 445nm and 455nm LEDs as the same batch.
  • The dual-band cutoff design suppresses common stray light in LED production (such as UV reflection from the chip substrate), avoiding mis-sorting. Additionally, the high damage threshold ensures stable performance during long-term high-power testing, reducing replacement frequency.

3. Core Parameter Comparison and Selection Guidelines

Key parameter requirements for different applications:

  • Fluorescence Microscopy Excitation
  • Central Wavelength Accuracy: ±2nm
  • Bandwidth Requirement: 10–20nm
  • Cutoff Depth: OD≥4
  • Damage Threshold: Medium-low (≤100mW/cm²)
  • Fluorescence Microscopy Emission
  • Central Wavelength Accuracy: ±5nm
  • Bandwidth Requirement: 30–50nm
  • Cutoff Depth: OD≥6
  • Damage Threshold: Low (≤50mW/cm²)
  • LED Wavelength Sorting
  • Central Wavelength Accuracy: ±1nm
  • Bandwidth Requirement: 5–8nm
  • Cutoff Depth: OD≥5
  • Damage Threshold: High (≥500mW/cm²)

Selection Recommendations:

  1. Prioritize Light Source Matching: When using blue LEDs as the excitation source, choose filters with a central wavelength strictly aligned with the LED's main peak (e.g., 450nm source matches 450±1nm filter).
  2. Balance Bandwidth and Signal Strength: In fluorescence imaging, slightly widen the emission filter bandwidth (e.g., 50nm) to enhance signal intensity, while ultra-narrow bandwidth (e.g., 5nm) is necessary for LED sorting to ensure wavelength resolution.
  3. Evaluate Long-Term Reliability: For high-power testing environments (such as industrial sorters), select hard-coat filters with a damage threshold ≥500mW/cm² to prevent performance drift due to coating aging.

By following these configurations, high-contrast imaging in fluorescence microscopy and consistent wavelength sorting in LED production can be achieved, while parameter optimization reduces system noise and maintenance costs.

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