BH-A11 Broad Bandpass Filter

BH-A11 is KUPO Optics’ precision dichroic filter, engineered to isolate the blue portion of the visible spectrum with exceptional purity and efficiency. Its advanced multi-layer dielectric coating provides a sharp, defined transmission window, making it ideal for applications in scientific imaging, color separation, and specialized illumination. The filter is designed to pass a high percentage of blue light while strictly blocking green and red wavelengths, and features a secondary transmission window in the near-infrared for dual-band applications.

At a 45° Angle of Incidence (AOI), the BH-A11’s performance is precisely controlled. The curve shows near-total rejection of UV light below 380 nm, then rapidly climbs to over 95% peak transmittance in the core blue-cyan region of 420–480 nm. At approximately 490 nm, the filter executes a steep cut-off, plummeting to less than 5% transmittance and maintaining this deep rejection across the entire green, yellow, and red spectrum (520–640 nm). Beyond this, a second transmission band opens in the near-infrared, rising to ~60% at 780 nm. The result is a stream of pure, high-intensity blue light, stripped of unwanted visible wavelengths but allowing for simultaneous NIR monitoring.

Key Advantages

• High-Purity Blue Transmission – With peak transmittance exceeding 95% in the 420–480 nm range, the BH-A11 ensures maximum throughput and intensity for critical blue-light applications.
• Exceptional Color Separation – The steep spectral edges create a clean, sharp cutoff between the transmitted blue and the rejected green/red wavelengths, preventing color contamination and enhancing contrast.
• Deep Green & Red Blocking – Near-zero transmittance across the 520–640 nm range provides an excellent signal-to-noise ratio for sensitive detectors and ensures color fidelity in imaging systems.
• Dual-Band Capability – A secondary transmission window in the near-infrared (NIR) allows a single optic to be used in systems that require simultaneous analysis or imaging in both the blue visible and NIR regions.
• Rugged & Stable Performance – The hard-oxide dielectric coating is environmentally stable and resistant to damage from heat, humidity, and repeated cleaning, ensuring a long operational life in demanding settings.
• Optimized for 45° AOI – Designed for use in beam-folding or color-splitting applications where a 45° angle is required, maintaining high performance without spectral shift.
• Rapid Customization – KUPO stocks common sizes, but our engineers can rapidly produce custom shapes, alternative substrates, or designs tuned for different AOIs or spectral requirements.

Typical Applications

• Fluorescence Microscopy & Bio-Imaging – Perfectly suited for isolating blue excitation wavelengths (e.g., for CFP, GFP) while effectively blocking longer-wavelength fluorescence bleed-through, thereby protecting sensitive samples.
• Color Separation & Projection – Ideal for use in 3-chip projectors or color-sorting systems to isolate the blue channel with high efficiency and purity, leading to brighter and more vivid images.
• Machine Vision & Industrial Inspection – Enhances contrast and feature detection by illuminating target objects with pure blue light, critical for inspecting materials with specific spectral responses.
• Photometry & Colorimetry – Used in scientific instruments to establish precisely defined lighting conditions or to calibrate sensors for accurate color measurement tasks.
• Theatrical & Architectural Lighting – Creates deeply saturated blue and cyan lighting effects with far greater efficiency and color purity than traditional absorptive gels.
• Scientific Instrumentation – Serves as a key component in spectrometers, flow cytometers, and other analytical instruments that require precise wavelength selection.

Need this spectral performance on a different substrate, with an AR-coated back surface, or with the NIR window blocked? Talk to KUPO Optics today—our engineering team can tailor the BH-A11 to your exact optical path and deliver prototypes fast.