产品: Longpass Filter
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Longpass Filter
Optical longpass filters are precision components designed to transmit longer wavelengths while blocking shorter wavelengths below a specific cut-on point. TIHOT Optics provides high-performance longpass filters spanning UV to IR wavelengths, featuring hard dielectric coatings for superior transmission in the passband and excellent blocking in the rejection band.
Key Features
Precise Cut-On Wavelength Control Cut-on wavelength range from 300 nm to 3000 nm, providing precise control over spectral separation with customizable edge positions for specific applications.
Excellent Long-Wave Transmission High transmission >90% in the passband region ensures maximum signal throughput for longer wavelengths with minimal optical loss and neutral color balance.
Superior Short-Wave Blocking Deep blocking up to OD6 in the rejection band effectively eliminates unwanted shorter wavelengths, ensuring high spectral purity and optimal signal-to-noise ratios.
Steep Edge Transition Sharp transition between blocking and passband region (typically <5% of cut-on wavelength) enables precise wavelength separation for demanding fluorescence and imaging applications.
Durable Hard Dielectric Coating Hard multilayer dielectric coating ensures long-term stability, environmental resistance, and maintains performance under demanding operating conditions and repeated cleaning.
Broad System Compatibility Compatible with fluorescence microscopy emission filtering, Raman spectroscopy, thermal imaging, and multi-spectral systems for versatile integration across optical platforms.
Typical Specifications
| Parameter | Specification Range | Description |
|---|---|---|
| Cut-On Wavelength (λc) | 300–3000 nm | Wavelength at 50% transmission point |
| Passband Transmission (T%) | >90% typical, up to >95% | Transmission efficiency above cut-on wavelength |
| Blocking Level | OD4–OD6 | Short-wavelength rejection below cut-on |
| Edge Steepness | <5% of λc typical | Transition width from 10% to 90% transmission |
| Blocking Range | 200 nm to λc | Extended UV-visible blocking specification |
| Substrate Material | Fused Silica, Borosilicate, BK7, IR Glass | Material selected by spectral region requirements |
| Coating Type | Hard dielectric multilayer | High durability and thermal stability |
| Diameter/Size | 5–100 mm (custom available) | Round or square shapes available |
| Surface Quality | 40–20 / 20–10 | Precision optical grade per MIL-PRF-13830B |
| AOI (Angle of Incidence) | 0°–10° | Edge shifts toward shorter wavelengths with angle |
| Operating Temperature | -40°C to +85°C | Stable performance across temperature range |
| Parallelism | <3 arcsec | Minimizes beam deviation in precision setups |
| Thickness Options | 1–5 mm | Standard and custom thickness available |
| Passband Flatness | >85% average transmission | Minimal ripple across passband region |
Applications
Flow Cytometry – Isolate emission wavelengths from multiple fluorescent labels in cell sorting and analysis systems, enabling simultaneous detection of 6–12 fluorescence parameters with minimal spectral overlap.
Astronomical Observation – Block shorter-wavelength sky glow and light pollution while transmitting Hα (656.3 nm), [OIII] (495.9/500.7 nm), and other emission lines for enhanced nebula and galaxy imaging in astrophotography.
Machine Vision Inspection – Eliminate blue and UV illumination while detecting red and infrared reflected signals in surface inspection, barcode reading, and quality control applications requiring color-specific imaging.
Medical Diagnostics – Filter excitation light in clinical analyzers, retinal imaging systems, and surgical visualization equipment requiring specific emission wavelength detection with high background rejection.
Optical Communication – Separate long-wavelength communication channels (1310 nm, 1550 nm) from monitoring and control signals in fiber optic systems and wavelength-division multiplexing (WDM) networks.
Filter Selection Guide
Fluorescence Microscopy Applications:
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- FITC/GFP Emission: 510 nm or 525 nm longpass
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- TRITC/Texas Red Emission: 590 nm or 610 nm longpass
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- Cy5/Alexa Fluor 647 Emission: 665 nm or 685 nm longpass
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- Multi-Band Systems: Consult for custom multi-edge longpass filters
Raman Spectroscopy Applications:
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- 532 nm Laser: 540 nm, 550 nm, or 560 nm longpass (depending on Stokes shift)
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- 633 nm Laser: 645 nm or 650 nm longpass
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- 785 nm Laser: 800 nm or 808 nm longpass
Thermal Imaging Applications:
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- Silicon Detectors: 780 nm or 800 nm longpass (block visible, transmit NIR)
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- InGaAs Detectors: 1000 nm or 1100 nm longpass
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- LWIR Cameras: 3000 nm longpass (block MWIR, transmit LWIR)
Custom Longpass Filter Solutions
TIHOT Optics offers comprehensive customization services to meet specific application requirements. Our engineering team can design and manufacture longpass filters with custom cut-on wavelengths, edge steepness specifications, blocking ranges, and physical dimensions tailored to your exact specifications.
Custom Options Available:
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- Custom cut-on wavelengths across 300–3000 nm range
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- Ultra-sharp edge transitions (<2% of cut-on wavelength)
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- Extended IR transmission (>2500 nm) with specialty substrates
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- Non-standard sizes and shapes (rectangular, square, custom diameters)
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- Multi-edge longpass designs for multi-band fluorescence systems
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- Enhanced coating designs for high-power illumination applications
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- Mounted filter assemblies with anti-reflection coated windows
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- Custom blocking depth requirements (OD7, OD8 at specific wavelengths)
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- Temperature-stabilized designs for precision instrumentation
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- Low-autofluorescence coatings for single-molecule detection
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- Dual-side AR coating for reduced back-reflection in imaging systems
Contact our technical sales team to discuss your requirements and receive a detailed quotation for custom longpass filter solutions. We provide full spectral characterization data including transmission curves, blocking performance, and angle-dependent measurements with all custom filters.
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