Narrow Band Interference Filters

Name: Narrow Band Interference Filters
Brand: PhotonEdge
SKU: PE-FILTER-NB-028
Availability: LimitedAvailability

Key Specifications

Filter Type	Narrow Band Interference (Bandpass)
Center Wavelength	Custom (200 - 2500 nm)
Bandwidth (FWHM)	1 nm - 40 nm
Peak Transmission	> 40% (standard) / > 90% (high-performance)
Blocking (OD)	OD 1-6 depending on design
Substrate Options	BK7 / UV Fused Silica / Borosilicate
Diameter Range	6 mm - 200 mm
Incidence Angle	0° (normal) / Custom AOI designs

What Is a Narrow Band Interference Filters?

Narrow band interference filters selectively transmit a specific wavelength band while blocking all other wavelengths. They work on the principle of thin-film interference, using precisely controlled multi-layer dielectric coatings to create constructive interference at the target wavelength and destructive interference elsewhere.

These filters can replace expensive spectrometers in applications where only a specific wavelength band needs to be isolated. They are widely used in fluorescence microscopy, Raman spectroscopy, laser line selection, environmental monitoring, and machine vision inspection systems.

When Should You Use This Product?

✔ Good Choice When

✓ Isolating specific fluorescence emission bands in microscopy
✓ Raman spectroscopy signal extraction (rejecting Rayleigh scatter)
✓ Laser line selection and cleanup
✓ Machine vision inspection at specific illumination wavelengths

⚠ Consider an Alternative When

✗ Broad wavelength bandpass needed (> 100nm) → Longpass or Shortpass Filter

✗ Variable attenuation rather than wavelength selection → Neutral Density Filter

✗ Multiple wavelength bands simultaneously → Dichroic Filter / Multiband Filter

✗ Very high spectral resolution (< 0.1nm) → Grating-based spectrometer

Available Optical Materials

Select the optimal substrate material based on your wavelength, environment, and budget requirements.

Material	Transmission	Key Advantage	Considerations
BK7 Substrate	VIS / NIR (350-2000nm)	Low cost, good for most visible applications	Not suitable for UV < 350nm
UV Fused Silica	UV / VIS / NIR (185-2100nm)	Required for UV center wavelengths	Higher cost than BK7
Borosilicate (B270)	VIS (400-700nm)	Economy choice for visible-only applications	Limited wavelength range

Not sure which material to choose?

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Optical Coating Options

Hard Dielectric Multi-Layer

Ion-beam sputtered or e-beam evaporated dielectric layers. High environmental stability, high LIDT.

Typical use: Laser systems, outdoor instruments, demanding environments

Soft Dielectric Multi-Layer

Conventional evaporated dielectric layers. Lower cost, adequate for lab environments.

Typical use: Laboratory instruments, indoor applications

Metal-Dielectric Combination

Mixed metal-dielectric designs for very wide blocking ranges.

Typical use: Applications requiring OD 4+ blocking

Absorbing Glass + Interference

Combined absorptive and interference designs for ultra-wide blocking.

Typical use: Fluorescence microscopy, Raman spectroscopy

How to Specify Your Coating

To select the right coating, please provide: (1) Operating wavelength, (2) Angle of incidence, (3) Required transmission or reflectivity, (4) Laser power density (if applicable), (5) Operating environment.

Engineering Considerations

Key factors to evaluate when specifying this optical component for your system.

Center Wavelength (CWL)

The peak transmission wavelength shifts toward shorter wavelengths as the angle of incidence increases. For non-normal incidence, specify the AOI so we can design the coating accordingly.

Bandwidth (FWHM)

Narrower bandwidth provides better spectral isolation but reduces total transmitted energy and increases cost. Typical choices: 1-3nm for Raman, 10-20nm for fluorescence, 20-40nm for machine vision.

Blocking (OD)

Optical density defines how well out-of-band light is suppressed. OD 3 means 0.1% transmission outside the passband. For fluorescence applications, OD 4-6 is often required to suppress excitation light.

Peak Transmission

Higher peak transmission means more signal. Narrow bandwidth designs trade peak transmission for selectivity. Typical values: 40-60% for narrow (< 5nm), 70-90% for moderate (10-40nm).

Angle of Incidence

For converging or diverging beams, the effective AOI varies across the beam, causing bandwidth broadening and center wavelength shift. Specify the beam cone angle for accurate performance prediction.

Temperature Stability

Dielectric coatings shift approximately 0.01-0.02 nm/°C. For precision applications in varying temperatures, specify the operating temperature range.

Have a Custom Optical Requirement?

Upload your drawing or describe your specification. Our engineering team will review and respond within 24 hours with a detailed quotation.

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Applications

Fluorescence Microscopy

Emission and excitation filters for specific fluorophore bands. Combined with dichroic mirrors for complete filter sets.

Raman Spectroscopy

Notch and bandpass filters for Rayleigh line rejection and Stokes/anti-Stokes signal extraction.

Machine Vision

Wavelength-specific filters for inspection systems using LED or laser illumination.

Environmental Monitoring

Gas analysis, water quality monitoring, and atmospheric sensing using specific absorption lines.

Manufacturing & Customization

PhotonEdge supports optical component sourcing, engineering review, and qualified manufacturing through our optical manufacturing network. We coordinate production, coating, and inspection to deliver components that meet your specifications.

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Prototype

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Low Volume

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Volume Production

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Custom Specification

Quality Assurance

Dimensional Inspection

Diameter, thickness, focal length verified per specification

Surface Quality

Scratch-dig inspection under calibrated illumination

Coating Verification

Spectrophotometric measurement of transmission/reflectance

Inspection documentation available according to project requirements. Certificates of Conformance, material test reports, and coating curves can be provided.

You May Also Need

Related Knowledge

Engineering Documentation

The following documentation is available upon request for qualified engineering projects:

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Dimensional Drawing

CAD & dimensional specs per your requirements

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Material Data Sheet

Material properties, transmission curves & certificates

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Coating Performance Curve

Spectrophotometric measurement data

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Inspection Report

Surface quality, flatness, centration & dimensional data

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Certificate of Conformance

CoC with full traceability per project requirements

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Custom Specification Sheet

Application-specific specification documentation

Documentation availability depends on project scope and order quantity. Request details during RFQ.

Ordering Information

Price Range

See Quote

Standard Lead Time

Ships within 1 week after payment

Custom Lead Time

Subject to engineering evaluation

MOQ

1 Piece

Samples

Available

Contact us for exact pricing based on your specifications.

Specification Parameters

Typical Specifications shown on this page are standard capabilities. Available Options include alternative materials and coatings. Custom Specifications are available per your drawing. Requirements beyond standard capability are marked Subject to Engineering Review.

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Frequently Asked Questions

What is the difference between narrow band and broadband filters?

Narrow band filters have bandwidth (FWHM) typically below 40nm and isolate a specific wavelength. Broadband filters pass a wider range of wavelengths. Narrow band filters are more selective but transmit less total energy.

Can I specify a custom center wavelength?

Yes. PhotonEdge designs custom narrow band filters for any center wavelength from 200nm to 2500nm. Provide your target wavelength, bandwidth, and blocking requirements for a custom design.

How does angle of incidence affect filter performance?

As the angle of incidence increases, the center wavelength shifts toward shorter wavelengths (blue shift). For converging beams, this causes bandwidth broadening. Always specify your beam geometry for accurate performance.

What does OD 4 blocking mean?

OD (Optical Density) 4 means the filter blocks 99.99% of light outside the passband (transmission < 0.01%). Higher OD values provide better blocking but may reduce peak transmission and increase cost.

What substrate should I choose?

For visible wavelengths (400-700nm), BK7 is the most economical choice. For UV center wavelengths (< 400nm), UV Fused Silica is required. For economy visible-only applications, B270 borosilicate glass is available.

Can these filters handle high-power laser?

Standard dielectric filters can handle moderate laser powers. For high-power applications, specify the laser power density and we will design with high-LIDT hard dielectric coatings.

What is the typical lead time for custom filters?

Standard catalog filters ship within 1-2 weeks, depending on quantity and specifications. Custom narrow band filter designs typically require 3-4 weeks for development and production, subject to change based on order specifics.

How do I specify a filter for fluorescence?

Provide: (1) excitation wavelength, (2) emission peak wavelength, (3) required bandwidth, (4) blocking OD at excitation wavelength, and (5) whether it is for excitation or emission path. We will recommend the optimal design.

Not Sure Which Specification You Need?

Describe your optical system and our AI Optical Engineer will help identify the right specifications, materials, and coatings for your application.

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Provide your requirements and our engineering team will respond within 24 hours with a detailed quotation.

Filter TypeCenter WavelengthBandwidth (FWHM)Peak TransmissionBlocking (OD)Substrate OptionsDiameter RangeIncidence Angle

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