470nm Bandpass Filters

470nm bandpass filters are designed to transmit a selected blue wavelength band centered near 470nm while reducing unwanted out-of-band light.

Applications:
- Blue LED source cleanup for fluorescence excitation, inspection, and illumination systems
- GFP/FITC/Alexa Fluor 488-type fluorescence excitation channels
- Detector-side blue signal isolation before cameras, photodiodes, PMTs, or spectrometers
- Broadband visible source filtering for blue-band optical measurement
- Display, lighting, and machine vision systems that need controlled blue illumination

Bandwidth options:
- 10nm and 20nm FWHM for tighter 470nm blue-band control
- 30nm and 40nm FWHM for balanced excitation power and background reduction
- 65nm, 70nm, and 120nm FWHM for broader blue illumination, imaging, or display-related use

Select the bandwidth based on the LED spectrum, excitation requirement, detector sensitivity, blocking range, and required blue signal level.

470nm blue LED or LED array

Use CWL 470nm with 20–40nm FWHM for blue LED source cleanup while keeping usable blue output.

470nm LEDs have broader emission than laser sources. A 20nm or 30nm FWHM filter can help define the blue illumination band for fluorescence excitation, inspection, or optical measurement. Use 40nm FWHM when the setup needs more blue signal while still reducing unwanted spectral components.

GFP/FITC/Alexa Fluor 488-type fluorescence excitation

Use CWL near 470nm with 20–40nm FWHM for blue excitation channels such as GFP/FITC/Alexa Fluor 488-type fluorescence systems.

For fluorescence microscopes, flow cytometers, or fluorescence detection systems, the 470nm filter is usually placed on the excitation side before the sample. The goal is to deliver useful blue excitation while reducing excitation-path leakage and crosstalk into the emission channel. The emission-side filter should be centered around the actual green emission band, not at 470nm.

Broadband visible source

Use CWL 470nm with 30–70nm FWHM to select a useful blue band from xenon, halogen, white-light, or other broadband visible sources.

For broadband visible illumination, the filter extracts a 470nm-centered blue band from a wider spectrum. Use 30–40nm FWHM when the setup needs a more defined blue band. Use 65–70nm FWHM when higher transmitted blue signal is more important for illumination, imaging, or detection.

Display, lighting, and blue illumination systems

Use CWL 470nm with 40–120nm FWHM when the goal is controlled blue output for lighting, display, or broad illumination.

For LED lighting, display modules, and blue illumination systems, wider filters can support stronger blue output while reducing unwanted spectral components outside the required band. Use 40–70nm FWHM for blue-band control, or 120nm FWHM when the system needs a broad blue transmission window.

Machine vision and camera imaging

Use CWL 470nm with 40–70nm FWHM for machine vision or camera imaging when the task needs blue-light contrast.

For CMOS or CCD camera imaging, 470nm filters can help isolate blue illumination and reduce unwanted ambient or background light. Wider filters are often practical when image brightness and contrast are more important than narrow spectral isolation.

US5804387A - FACS-optimized mutants of the green fluorescent protein (GFP)

Context: This patent describes creating mutant versions of the Green Fluorescent Protein (GFP) that are brighter and fold more efficiently than the wild-type protein, specifically for use in Flow Cytometry (FACS).

Usage of Filter: The filter is used as an excitation filter to isolate the blue region of the light spectrum.

Function: It targets the minor excitation peak of the wild-type GFP (which occurs at roughly 470nm) or the shifted peaks of specific mutants.

Result: This allows researchers to monitor GFP levels using standard FITC (fluorescein) filter sets found in common laboratory equipment, enabling the efficient sorting of cells based on gene expression without needing specialized UV light sources (which were required for the major 395nm peak of wild-type GFP).

US20110205494A1 - Spectral Separation Filters For 3D Stereoscopic D-Cinema Presentation

Context: This patent details a digital cinema projection system that uses spectral division to create 3D images (a technique often associated with Dolby 3D).

Usage of Filter: The filter operates as a spectral separation filter (dichroic filter) situated in the projection path or the viewer's glasses.

Function: It precisely "slices" the blue portion of the visible spectrum. For example, it might pass a narrow band centered at 470nm for the "Left Eye" blue channel, while blocking that specific wavelength for the "Right Eye" (which might use a slightly shifted blue, e.g., 490nm).

Result: This creates two distinct images projected simultaneously on a single screen. When viewers wear the passive filtered glasses, each eye sees only its designated image, resulting in a high-quality stereoscopic 3D effect with accurate color representation and minimal "ghosting" (crosstalk).

US11169131B2 - System for nitrogen dioxide gas analysis

Context: This patent describes a system for detecting Nitrogen Dioxide (NO₂) concentrations in gas mixtures using optical absorption spectroscopy.

Usage of Filter: The filter is used as an optical interference filter (or bandwidth-limiting element) within the detection cavity.

Function: It restricts the light source to a specific measurement band around 470nm. While NO₂ absorbs light across a broad blue spectrum (400-500nm), selecting 470nm specifically helps avoid spectral interference from other gases like glyoxal (which has strong absorption near 450nm-455nm but negligible absorption at 470nm).

Result: The system achieves highly accurate and selective quantification of NO₂ (in parts per billion), ensuring that readings are not falsely inflated by the presence of other common atmospheric pollutants.

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