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Unlike absorptive filters that convert unwanted light to heat (risking thermal damage in high-power setups), dichroic filters achieve separation with minimal energy absorption—typically <5% of incident light—making them ideal for high-power laser systems, heat-sensitive imaging equipment, and continuous-operation industrial tools. Our dichroic filters are engineered for versatility, supporting both standard configurations (e.g., 45° incidence for beam splitting) and custom designs (e.g., multi-band separation for hyperspectral imaging), ensuring compatibility with laser systems, microscopy setups, and spectral analysis equipment across industries. With applications ranging from automotive LiDAR to space-borne sensors, our filters meet rigorous environmental standards, including resistance to humidity, temperature cycling, and mechanical vibration.
Dual Functionality: Simultaneously acts as a shortpass and longpass filter, with sharp cut-on/cut-off transitions (e.g., 740nm shortpass + 940nm longpass) that minimize overlap between reflected and transmitted wavelength ranges. For example, a 740nm shortpass/940nm longpass dichroic reflects visible light (400–740nm) for imaging while transmitting NIR light (940–1700nm) for distance measurement in LiDAR systems .
Broad Wavelength Compatibility: Operates within the 175–3200nm+ range, with options for UV (175–400nm), visible (400–700nm), and infrared (700–3200nm) separation. UV-optimized models use fused silica substrates to avoid UV-induced substrate absorption, while IR models utilize germanium (Ge) or zinc selenide (ZnSe) substrates for enhanced MIR transmission .
Large Aperture Options: Available in 3–400mm diameter sizes to accommodate diverse applications. Small apertures (3–25mm) suit compact laser modules (e.g., handheld laser pointers), while large apertures (100–400mm) are designed for high-power laser beam combiners (e.g., 10kW fiber laser cutting machines) and projection systems (e.g., large-venue LED projectors) .
Hard Refractory Coatings: Utilize materials like titanium dioxide (TiO₂) and silicon dioxide (SiO₂) to ensure high damage thresholds—up to 10J/cm² @ 1064nm, 10ns pulses—critical for ultrafast laser harmonic beamsplitting (e.g., separating 532nm second harmonic from 1064nm fundamental in Nd:YAG lasers) .
Surface Quality: Maintains 20-10 or 10-5 standards (per MIL-PRF-13830B) to prevent signal degradation in imaging applications. A 10-5 surface reduces scatter in fluorescence microscopy, ensuring clear separation of excitation (e.g., 488nm) and emission (e.g., 520nm) wavelengths .
Beam Combining/Splitting: Efficiently combines multiple laser wavelengths (e.g., 532nm green and 1064nm infrared) at 45° incidence for multi-source equipment, such as laser marking machines that use dual wavelengths for deep engraving on metal and plastic. Also splits laser beams into multiple paths for parallel processing (e.g., semiconductor wafer dicing with 10 parallel laser beams) .
Heat Management: Removes near-infrared (NIR) heat from optical systems using heat-reflecting "hot mirrors"—dichroic filters that reflect NIR (700–1700nm) while transmitting visible light. These are widely used in digital projectors to prevent heat damage to LCD/DLP chips, extending component lifespan by 50% .
Fluorescence Microscopy: Separates excitation and emission wavelengths to enhance image contrast. For example, a 488nm excitation dichroic reflects 488nm light to illuminate samples while transmitting 500–550nm emission light to the detector, eliminating excitation light glare and improving signal-to-noise ratio by >10x .
Color Separation: Enables precise RGB channel isolation in advanced imaging systems, such as high-definition cameras for medical endoscopy. Dichroic filters split white light into red (620–700nm), green (500–560nm), and blue (440–480nm) channels, ensuring accurate color reproduction for tissue diagnosis .
UV Water Purification: Monitors mercury lamp effectiveness in real-time using 254nm dichroic filters. These filters transmit 254nm UV light (the wavelength most effective for killing bacteria) to a sensor, while reflecting other wavelengths, allowing continuous monitoring of lamp output and timely replacement (typically when output drops below 70% of initial intensity) .
Defense Surveillance: Integrates into targeting systems for wavelength-specific threat detection. For instance, military night-vision goggles use dichroic filters that transmit 850–940nm NIR light (invisible to the naked eye) while blocking visible light, enabling stealthy target acquisition in low-light conditions .
Q: How do dichroic filters differ from standard color filters?
A: Unlike absorptive color filters that convert unwanted light to heat (e.g., a red color filter absorbs green/blue light, generating heat that can warp plastic substrates), dichroic filters reflect unused wavelengths (e.g., a red dichroic reflects green/blue light away from the system) with minimal thermal buildup. This makes them critical for high-power laser applications (e.g., 1kW laser welding) where heat damage would render absorptive filters inoperable. Additionally, dichroic filters offer sharper cut-off edges (<5nm transition) compared to color filters (>20nm transition), ensuring precise wavelength separation .
Q: Can dichroic filters be used at non-normal incidence?
A: Yes, while optimized for normal incidence (0°), custom versions can be produced for 45° operation in beam-splitting setups—one of the most common use cases. At 45° incidence, the cut-off wavelength shifts slightly (typically +5–10nm for visible wavelengths), which we account for in custom designs. For example, a 500nm cut-off filter at normal incidence can be adjusted to 508nm for 45° use, ensuring alignment with target wavelengths. We also offer filters for 30° and 60° incidence to fit specialized optical layouts .
Q: What is the maximum laser power these filters can handle?
A: Our hard-coated dichroic filters feature high damage thresholds, with standard models supporting up to 5J/cm² @ 1064nm, 10ns pulses (suitable for Nd:YAG laser harmonics) and 1kW/cm² continuous-wave (CW) power (for fiber lasers). For ultrafast lasers (e.g., femtosecond lasers with <100fs pulses), we offer enhanced coatings with LIDT up to 20J/cm² @ 800nm, 100fs pulses, designed to withstand the intense peak power of short pulses. We recommend specifying laser parameters (wavelength, pulse duration, repetition rate) during customization to ensure optimal performance .
Q: Are custom wavelength combinations available?
A: Absolutely. We offer tailored solutions like multi-band dichroics that function as both shortpass and longpass filters (e.g., 740nm shortpass + 1020nm longpass) for applications requiring simultaneous separation of three wavelength ranges. Custom options include adjusting cut-on/cut-off wavelengths (e.g., 650nm shortpass + 800nm longpass for automotive night vision), adding anti-reflection (AR) coatings on the transmitted side (reducing reflection loss to <0.5%), and integrating polarization control (e.g., reflecting p-polarized light while transmitting s-polarized light) for 3D imaging systems .
