Longpass Filter
Longpass Filters are precision optical filters designed to transmit wavelengths above a specified cut-on wavelength while blocking shorter wavelengths. Using multilayer dielectric coatings, longpass filters provide accurate spectral separation and high transmission in the passband. Chenyu Optics manufactures longpass filters in BK7 and fused silica with custom cut-on wavelength design.
Longpass Filter Overview
Longpass Filters are precision optical filters designed to transmit wavelengths above a specified cut-on wavelength while blocking shorter wavelengths.
Using multilayer dielectric coatings, longpass filters provide accurate spectral separation and high transmission in the passband. They are widely used in fluorescence imaging, spectroscopy, machine vision, infrared sensing and optical measurement systems.
Chenyu Optics supports custom longpass filter manufacturing according to customer drawings, including custom substrate material, dimensions, cut-on wavelength and coating design for prototype and repeat production.
Key Advantages of Longpass Filter
Fluorescence Imaging & Spectroscopy Systems
Longpass filters are widely used for precise spectral separation in fluorescence imaging, spectroscopy equipment, machine vision and infrared sensing systems.
Typical Specifications of Longpass Filter
| Material Options | BK7, Fused Silica |
|---|---|
| Coating Type | Dielectric longpass coating |
| Optical Function | Short wavelength blocking / Long wavelength transmission |
| Cut-on Wavelength | Customizable |
| Transmission Range | Above designed wavelength |
| Blocking Range | Below designed wavelength |
| Surface Quality | High precision optical finish |
| Coating Performance | Precision controlled |
Spectral Transmission Curve (Typical)
Why Choose Chenyu Optics for Longpass Filter
Chenyu Optics focuses on drawing-based precision filter manufacturing for fluorescence, spectroscopy, machine vision and industrial optical systems. We support prototype verification, small-batch production and repeat manufacturing for non-standard longpass filters.
Manufacturing Capability for Longpass Filter
Precision Polishing
High surface quality processing for stable filter performance.
Dielectric Coating
High performance multilayer dielectric coating for precise cut-on wavelength control.
Inspection & Packaging
Strict quality control on cut-on wavelength and blocking performance, with clean protective packaging before shipment.
Custom Longpass Filter Options
Longpass Filter Material Comparison
| BK7 | Fused Silica | |
|---|---|---|
| Thermal Stability | Moderate thermal stability | Excellent, low thermal expansion |
| Mechanical Notes | Widely available, cost-effective substrate | High homogeneity, good UV to NIR transmission |
| Typical Use | General visible-range longpass filtering, cost-sensitive systems | UV to NIR longpass systems, high-precision applications |
| Selection Note | Preferred for general applications with lower cost requirements | Preferred when broader spectral range and higher precision are required |
Applications of Longpass Filter
Fluorescence Imaging Systems
Spectral separation for fluorescence excitation and emission paths.
Spectroscopy Equipment
Precise cut-on filtering for spectroscopic measurement systems.
Machine Vision Systems
Wavelength blocking for machine vision and inspection equipment.
Infrared Sensing Systems
Longpass filtering for infrared detection and sensing applications.
Biomedical Imaging Systems
Spectral edge filtering for biomedical imaging instruments.
Optical Measurement Systems
Precision spectral filtering for measurement and metrology equipment.
Longpass Filter FAQ
What is the function of a longpass filter?
A longpass filter transmits wavelengths longer than the designed cut-on wavelength while blocking shorter wavelengths.
What parameters define a longpass filter?
Important parameters include cut-on wavelength, transmission range, blocking range, optical density, and incident angle.
Can longpass filters be customized?
Yes. Custom cut-on wavelengths, dimensions, substrates, and coating designs are available.
Does incident angle affect longpass filter performance?
Yes. The spectral edge may shift with incident angle, so coating design should match the optical system.
What information should I provide for a quotation?
Please provide cut-on wavelength, substrate material, dimensions, angle of incidence, quantity and drawing if available.
Where can I learn more about longpass filter design?
Additional information on longpass filter design can be found from Edmund Optics.
Related Products for Longpass Filter
Need Custom Longpass Filters?
Send us your cut-on wavelength, substrate, dimensions, coating requirements and quantity. Chenyu Optics will review the optical and mechanical specifications and provide a suitable longpass filter manufacturing suggestion.