BP520nm Bandpass Filter | FWHM 13nm, Thickness 2.0mm, OD3+ Blocking

The BP520-13nm-2.0mm bandpass filter represents the pinnacle of precision optical filtering technology, combining ultra-narrow spectral selectivity with exceptional out-of-band rejection. This advanced bandpass filter features an extraordinarily narrow 13nm full width at half maximum (FWHM) centered at 520nm, delivering unparalleled wavelength discrimination for demanding multi-channel fluorescence applications. With blocking performance exceeding optical density 3.3 (transmission less than 0.05%) across the 350-1100nm range, this filter enables exceptional signal isolation in complex spectral environments. The robust 2.0mm substrate thickness ensures mechanical stability and thermal management for high-power applications. Manufactured by OPTOStokes using state-of-the-art high precision coating technology, this filter meets the most stringent requirements of research laboratories and precision instrument manufacturers worldwide.

Technical Specifications

The BP520-13nm-2.0mm filter achieves exceptional spectral performance through advanced multi-cavity coating design and precision manufacturing processes. The following table details the complete technical specifications:

Key Performance Features

This green light filter achieves performance levels that position it among the most advanced optical filters available for green spectral region applications. The ultra-narrow 13nm FWHM provides exceptional wavelength discrimination, enabling separation of closely spaced emission lines that would be indistinguishable with conventional 20-30nm bandpass filters. This superior spectral resolution is essential for multi-color fluorescence microscopy, multiplexed PCR detection, and high-resolution spectroscopy applications where spectral overlap between adjacent channels must be minimized.

Peak transmission exceeding 90% within the narrow 518-524nm passband ensures maximum signal throughput despite the restrictive bandwidth. This high transmission efficiency is achieved through advanced coating optimization algorithms and precision layer thickness control during deposition. The result is exceptional signal-to-noise ratio in photon-limited applications, where every collected photon contributes to measurement accuracy and detection sensitivity.

The extraordinary blocking performance with transmission below 0.05% (optical density greater than 3.3) represents a significant advancement over conventional optical filters typically specified at optical density 3 or 4. This deep blocking extends across the full 350-1100nm range, effectively eliminating UV autofluorescence, suppressing excitation light leakage, blocking adjacent fluorescence channels, and rejecting near-infrared detector noise. The comprehensive rejection ensures clean signal detection even in challenging measurement scenarios involving bright excitation sources, highly concentrated samples, or detectors with broad spectral sensitivity.

The robust 2.0mm substrate thickness provides enhanced mechanical stability compared to thinner alternatives, making this filter particularly suitable for high-power laser applications, temperature-variable experimental conditions, and precision optical mounts requiring rigid substrates. The increased thickness improves thermal dissipation, reducing temperature-induced wavelength shifts during extended operation. The substantial substrate also facilitates secure mounting in precision optical assemblies without risking deformation or stress-induced birefringence.

Applications

The BP520-13nm-2.0mm bandpass filter excels in advanced scientific and industrial applications demanding the highest levels of spectral precision and signal purity:

Quantitative PCR and Real-Time PCR Detection: This filter provides optimal performance for PCR detection systems utilizing FAM (6-carboxyfluorescein), SYBR Green I, and other green-emitting fluorescent reporters. The ultra-narrow 13nm bandwidth isolates FAM emission at 520nm while completely rejecting crosstalk from blue-shifted dyes like VIC (538nm) and yellow-shifted dyes like HEX (556nm). This precise spectral discrimination enables accurate multiplexed detection in multi-color qPCR assays used for gene expression analysis, SNP genotyping, pathogen detection, and clinical diagnostics. The high OD filter blocking performance ensures that excitation light from 470-490nm blue LEDs is completely suppressed, preventing detector saturation and baseline drift during thermal cycling.

Multi-Channel Fluorescence Microscopy: Advanced fluorescence imaging applications utilizing five or more simultaneous fluorescence channels require extremely narrow bandpass filters to prevent spectral crosstalk. The BP520 filter enables precise detection of FITC (Fluorescein Isothiocyanate), GFP (Green Fluorescent Protein), and Alexa Fluor 488 emissions while maintaining complete separation from blue CFP channels and yellow-green TRITC channels. Research applications including super-resolution microscopy, FRET (Fluorescence Resonance Energy Transfer) imaging, and live-cell multi-parameter tracking benefit from the enhanced spectral purity this filter provides. The high optical density blocking eliminates autofluorescence background and scattered excitation light, dramatically improving contrast and enabling visualization of dim cellular structures.

Flow Cytometry and High-Parameter Cell Analysis: State-of-the-art flow cytometry systems now routinely analyze 15-30 fluorescence parameters simultaneously, requiring unprecedented spectral resolution to distinguish adjacent fluorophore emissions. The 530nm filter region is particularly crowded in multi-color flow panels, with numerous green-yellow fluorophores clustered between 515-545nm. The BP520 filter's 13nm bandwidth provides the spectral precision necessary to isolate specific fluorophore emissions and minimize compensation requirements. Clinical applications including immunophenotyping, minimal residual disease detection, and rare cell enumeration rely on this filter's performance for accurate cell population discrimination.

Laser Line Filtering and Spectral Cleanup: Frequency-doubled Nd:YAG lasers emitting at 532nm and argon-ion lasers with strong 514nm lines require precise wavelength selection and amplified spontaneous emission (ASE) suppression. The BP520 filter effectively isolates the desired laser wavelength while rejecting adjacent plasma lines and broadband ASE background. Raman spectroscopy systems benefit from this filter's deep blocking performance, which prevents laser scatter and sample fluorescence from overwhelming weak Raman signals. Applications include chemical analysis, materials characterization, and pharmaceutical quality control.

Plate Reader and High-Throughput Screening Instruments: Automated microplate readers used in drug discovery, enzyme kinetics, and bioassay development require reliable fluorescence detection across 96, 384, or 1536-well formats. The BP520 filter enables accurate quantification of fluorescein-based assays, green fluorescent protein expression, and fluorogenic substrate reactions. The narrow bandwidth reduces well-to-well crosstalk in high-density plates, while the high blocking performance ensures low background readings and extended dynamic range. Pharmaceutical research laboratories conducting compound screening and assay development benefit from the reproducible performance and long-term stability this filter provides.

Confocal and Multiphoton Microscopy: Laser scanning microscopy techniques demand exceptional out-of-band blocking to prevent laser scatter and photomultiplier tube damage. The BP520 filter's optical density greater than 3.3 provides robust protection while efficiently transmitting green fluorophore emissions. Two-photon microscopy applications benefit from the extended near-infrared blocking, which suppresses scattered excitation light from 800-1100nm titanium:sapphire and OPO laser sources.

Customization and Advanced Engineering

OPTOStokes recognizes that cutting-edge research instruments and precision analytical systems often require customized optical solutions optimized for specific performance criteria. Our engineering team works collaboratively with customers to develop tailored filter designs:

Spectral Fine-Tuning: While the standard 13nm FWHM provides exceptional spectral resolution, bandwidth can be further narrowed to 10nm for ultimate wavelength discrimination in ultra-dense multi-color applications, or widened to 15-18nm for applications prioritizing signal strength over spectral purity. Center wavelength can be precisely tuned across the 515-525nm range with sub-nanometer accuracy to match specific fluorophore emission maxima, laser wavelengths, or LED source characteristics. Multi-band filter designs combining the BP520 passband with complementary blue and red regions are available for simplified multi-color detection systems.

Enhanced Blocking Specifications: For applications requiring even deeper out-of-band rejection, we can design filters achieving optical density greater than 4 (transmission less than 0.01%) or optical density greater than 5 (transmission less than 0.001%) in critical spectral regions. Extended blocking ranges covering 300-1300nm accommodate applications with near-infrared laser sources or silicon-based detectors sensitive beyond 1100nm.

Dimensional and Mounting Options: Standard circular formats are available in diameters from 12.5mm to 50mm, with square, rectangular, and custom shapes manufactured to precise dimensional tolerances. The 2.0mm thickness can be adjusted to 1.0mm for compact systems, 1.5mm for balanced performance, or 3.0mm for maximum rigidity in demanding mechanical environments. Filters can be supplied unmounted, or pre-mounted in threaded cells, filter cubes, filter wheels, and proprietary mechanical interfaces. Black edge coating eliminates scattered light from filter edges in critical imaging applications.

Angular Performance Optimization: Standard filters are optimized for 0-degree angle of incidence, but we can design filters for specific non-zero angles including the common 45-degree dichroic configurations used in fluorescence microscopy filter cubes. Angular performance data including wavelength shift and transmission variation across ±5 degrees can be provided to support tolerance analysis and optical design verification.

Environmental and Durability Enhancements: Applications in extreme environments benefit from environmental hardening including extended temperature ranges from -50°C to +100°C, high humidity resistance with salt spray tolerance per MIL-STD-810, and enhanced coating adhesion for vibration and shock resistance. Laser damage threshold testing and certification can be provided for high-power laser applications requiring guaranteed performance at specified power densities.

The OPTOStokes Quality Advantage

OPTOStokes has earned recognition as a premier manufacturer of ultra-narrow bandpass filters through relentless focus on coating precision, spectral accuracy, and manufacturing consistency. Our advanced ion-assisted deposition systems employ real-time optical monitoring and automated thickness control, ensuring layer-by-layer accuracy essential for achieving narrow bandwidth and deep blocking specifications. This technological capability enables us to manufacture filters with spectral tolerances that exceed industry standards.

Every filter undergoes comprehensive spectral characterization using research-grade spectrophotometers with sub-nanometer resolution and absolute accuracy traceable to national standards. Full transmission curves from 300nm to 1200nm are measured and documented, verifying center wavelength, FWHM, peak transmission, and blocking performance. Statistical process control monitors coating uniformity across production runs, ensuring batch-to-batch consistency for customers requiring matched filter sets or replacement filters maintaining identical spectral characteristics.

Quality assurance extends beyond spectral performance to encompass cosmetic quality, dimensional accuracy, and long-term environmental