Narrow Bandpass Filter
Product introductionOptical lenses that suppress light sources, sensors, and natural light, and separate out a specific monochromatic spectrum. Narrowband filters are filters that relatively cut off i
A narrow band optical filter is a type of optical filter that allows the transmission of a very specific and limited range of wavelengths (colors) of light while blocking or significantly attenuating all other wavelengths. These filters are characterized by their high spectral selectivity, which means they have a narrow bandwidth – typically measured in nanometers (nm) – and a well-defined center wavelength.
Key Features of Narrow Band Optical Filters:
1. Center Wavelength (λc): This is the primary wavelength that the filter is designed to transmit. It's the peak of the transmission spectrum.
2. Bandwidth (Δλ): The bandwidth defines how wide the range of transmitted wavelengths is. A narrow bandwidth implies high wavelength selectivity. For instance, a filter with a 10 nm bandwidth centered at 532 nm would only allow light around that green wavelength to pass through.
3. Transmission Efficiency: This refers to how much of the incident light within the passband is transmitted through the filter. High-quality filters aim for maximum transmission within the passband.
4. Blocking Range: The range of wavelengths outside the passband where the filter effectively blocks or absorbs light. A good narrow band filter will have deep blocking (low transmission) outside its passband to minimize unwanted light.
Applications of Narrow Band Optical Filters:
Narrow band filters find applications across various fields due to their ability to isolate specific wavelengths:
1. Spectroscopy: In analytical chemistry and astronomy, they help identify chemical compositions by isolating characteristic emission or absorption lines.
2. Imaging: In photography, astronomy, and medical imaging, they enhance contrast by selectively allowing the passage of specific wavelengths associated with certain features or substances.
3. Laser Systems: They are crucial in laser applications to clean up laser beams by removing unwanted spectral components, ensuring the laser operates at a precise wavelength.
4. Fluorescence Microscopy and Flow Cytometry: By selectively transmitting the excitation or emission wavelengths of fluorescent dyes, they improve signal-to-noise ratios and enable accurate detection.
5. Environmental Monitoring: They can be used in sensors to detect specific pollutants or measure atmospheric conditions by isolating wavelengths absorbed or emitted by target substances.
Types of Narrow Band Optical Filters:
- Interference Filters: These use multiple layers of thin films (dies) to create interference effects that selectively reflect or transmit certain wavelengths. They are commonly used for narrow band filtering due to their high precision and adjustability.
- Dichroic Filters: While dichroic filters can be broader, specialized designs can achieve narrow bands. They work based on the principle of dichroism, where materials absorb different wavelengths differently.
- Absorption Filters: These filters contain materials that selectively absorb unwanted wavelengths. They are less common for very narrow bands due to lower transmission efficiency and potential heating issues.
General application
Application | CWL | Tp | FWHM | Blocking wavelength |
Semiconductor package | 635m | 635±5nm@Te90% | 35±5nm | 350-1100nm@T<0.01% |
Laser rangefinder | 905nm | 905±5nm@T>90% | 20nm | 350-1100nm@T<0.01% |
Barcode scanning | 650nm | 650±8nm@T>90% | 50nm | 350-1100nm@T<0.01% |
Fingerprint recognition | 530nm | 530±3nm@T>90% | 25nm | 350-1100nm@T<0.01% |
Biometric identification | 850nm | 850±3nm@T>80% | 20nm | 350-1100nm@T<0.01% |
Criminal investigation lightsource | 450nm | 4503nm@T>80% | 20nm | 350-1100nm@T<0.01% |
Wheel aligner | 940nm | 940±5nm@T>85% | 35nm | 350-1100nm@T<0.01% |
Electronic whiteboard | 808nm | 808±3nm@T>85% | 40nm | 350-1100nm@T-0.01% |
Specification
Coating | IAD dielectric hard coating. combined filter |
Peak transmittance(Tp) | 95%，90%，85%，80%。70%。 |
FWHM | 8nm，10nm，15nm，20nm， |
Surface quality | 40-20(S/D) |
Clear aperture | >95% |
OD | OD2，OD3，OD4，OD5，OD6 |
Thickness | 0.3mm，0.55mm，0.7mm.1.0mm， |
Cut-off wavelength range | 200nm-A Centre Wavelength-1100nm |
Environmental testing | MIL-STD-810F |
Material | (K 9， BK 7.B 270， D263T， colored glass.etc) |
Round | Φ3mm - Φ110mm |
Square | 2mm*2mm -146mm*146mm |
Custom Narrow Bandpass Filter Specification Sheet
Bandpass Filter Design Parameters
- Type: __Narrow Bandpass Filter__
- Application: ____________________________ (e.g., Fluorescence analysis, laser line cleaning, astronomy)
Transmission Specifications
- Center Wavelength (λc): ______ nm
- Bandwidth (FWHM): ≤ ______ nm (Full Width at Half Maximum)
- Peak Transmission: ≥ _______%
- Out-of-Band Rejection: ≥ _______ dB (Desired blocking level outside passband)
Spectral Performance
- Tolerance on Center Wavelength: ± ______ nm
- Slope of Band Edges: ______ nm/nm (Describes the sharpness of transition from passband to stopband)
Substrate & Coating Properties
- Substrate Material: ________________________ (E.g., BK7, fused silica, CaF2)
- Coating Technology: ____________________ (E.g., Dielectric, interference-based)
- Surface Quality: __________________________ (Scratch-Dig standard)
- Thickness: ______________________________ mm (If specific requirement)
Physical Characteristics
- Diameter/Size: __________________________ mm (Or specify shape and dimensions)
- Thickness Tolerance: ± ______ mm (If applicable)
- Parallelism: ± ______ ° or ______ fringes
- Edge Treatment: __________________________ (E.g., Beveled, chamfered)
Environmental Requirements
- Operating Temperature Range: From ______ °C to ______ °C
- Storage Temperature Range: From ______ °C to ______ °C
- Humidity Resistance: _______________________% RH
Additional Requirements or Tests
- Angular Dependence Test: Yes / No
- Custom Mounting Options: __________________
- Laser Damage Threshold (if applicable): ______ W/cm²
Notes or Special Instructions
- __________________________________________________________
- __________________________________________________________
This comprehensive list of specifications enables the accurate fabrication of a narrow bandpass filter tailored to your exact application requirements, ensuring high spectral purity and transmission efficiency. Upon receiving the completed specification sheet, our team can proceed with the design, coating, and production process, followed by meticulous quality checks and prompt delivery.