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What is a Bandpass filter: A filter that only allows light within a specific target wavelength range to pass through while blocking the spectra on both sides of the passband is called a Bandpass filter.
The core function of a bandpass filter is to precisely transmit the target spectral band while efficiently blocking stray spectra on both sides of the passband. According to the working wavelength range, they can be divided into ultraviolet (UV), visible (Vis), near-infrared (NIR), and mid-to-far infrared (IR) bandpass filters. The general parameters of a bandpass filter (center wavelength CWL, full width at half maximum FWHM, peak transmittance T%, optical density OD, blocking range) form the basis for selection; different application scenarios have significant differences in the spectral performance, tolerance requirements, environmental adaptability, and structural form of the filter, which directly determine the filter's design scheme and structure.
Optical principle: Dielectric thin-film bandpass filters are usually based on the Fabry-Perot (FP) interference cavity principle. They are made by alternately stacking high refractive index (H) and low refractive index (L) dielectric layers to form an optical resonant cavity. The optical thickness of the layers is an integer multiple of a quarter of the reference wavelength λ/4 (nd = λ/4, where n is the refractive index). Light at the reference wavelength undergoes constructive interference at the layer interfaces, maximizing transmission and forming the passband, while light at non-reference wavelengths undergoes destructive interference and is strongly reflected, creating the stopband outside the passband.
Bandpass filter products use Ion-Assisted Deposition (IAD) or Ion Beam Sputtering (IBS) coating technology (except for ultraviolet and infrared bands). The film structure is solid and dense, with stable working wavelengths, suitable for use in complex environments like indoors and outdoors. Depending on the working wavelength, they can be divided into ultraviolet band-pass filters, visible light band-pass filters, near-infrared band-pass filters, and mid-to-far-infrared band-pass filters. Based on the number of passbands, they can be single-band, dual-band, or multi-band filters. We select suitable coating materials, coating processes, film system designs, and thickness monitoring schemes based on a combination of factors like working wavelength, spectral bandwidth, incidence angle, and background suppression to customize products that meet customer needs. A considerable portion of band-pass filters is also available in stock, and we welcome inquiries. Our company has a team with rich experience in optical processing and coating technology, capable of handling everything from sample development to mass production. We also provide free technical consultation and assessments of product performance and production feasibility.
Typical application scenarios: Fluorescence signal detection in the biomedical field (fluorescence microscope, flow cytometer, PCR, biochemical analyzer); Optical imaging and machine vision (industrial camera, security monitoring, microscopic imaging, vehicle-mounted vision); Spectral analysis applications (Raman spectroscopy, infrared spectroscopy, ultraviolet spectroscopy, gas detection); Laser applications (LiDAR, laser ranging, laser medical applications, laser pointing).
| Select Bandpass Filters | |||||
|---|---|---|---|---|---|
| UV Bandpass Filters CWL:200 - 400 nm | Vis Bandpass Filters CWL:400 - 700 nm | NIR Bandpass Filters CWL:700 - 2000 nm | IR Bandpass Filters CWL:2500 - 12 000 nm | Laser line Filters FWHM:2-5nm bandwidth | Narrow Bandpass Filters FWHM:6-10nm bandwidth |
| We can customize bandpass filters with other central wavelengths, spectral bandwidths, and size specifications. If you need a quote, please Contact。 | |||||
Vis~NIR Bandpass filters
| Product No.# | Specifications | Coating | Price/pcs |
|---|---|---|---|
| BP405-20 | CWL(nm):405±2，FWHM(nm):20±2，Tpeak >80%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP460-40 | CWL(nm):460±4，FWHM(nm):40±4，Tpeak >90%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP470-30 | CWL(nm):470±3，FWHM(nm):30±3，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP485-20 | CWL(nm):485±2，FWHM(nm):20±2，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP530-30 | CWL(nm):530±2，FWHM(nm):30±2，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP535-40 | CWL(nm):535±3，FWHM(nm):40±3，Tpeak >90%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP570-30 | CWL(nm):570±2，FWHM(nm):30±2，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP615-30 | CWL(nm):615±2，FWHM(nm):30±2，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP620-40 | CWL(nm):620±4，FWHM(nm):40±4，Tpeak >90%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP630-30 | CWL(nm):630±2，FWHM(nm):30±2，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP650-30 | CWL(nm):650±2，FWHM(nm):30±2，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP660-20 | CWL(nm):660±2，FWHM(nm):20±2，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP685-25 | CWL(nm):685±2，FWHM(nm):25±2，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP685-40 | CWL(nm):685±4，FWHM(nm):40±4，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP700-30 | CWL(nm):700±3，FWHM(nm):30±3，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP730-30 | CWL(nm):730±3，FWHM(nm):30±3，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP800-30 | CWL(nm):800±3，FWHM(nm):30±3，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP810-30 | CWL(nm):810±3，FWHM(nm):30±3，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP850-50 | CWL(nm):850±5，FWHM(nm):50±4，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP905-20 | CWL(nm):905±2，FWHM(nm):20±2，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP940-25 | CWL(nm):940±2，FWHM(nm):25±2，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP940-90 | CWL(nm):940±5，FWHM(nm):90±5，Tpeak >90%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP980-40 | CWL(nm):980±5，FWHM(nm):40±5，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP1064-15 | CWL(nm):1064±2，FWHM(nm):15±2，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP1064-30 | CWL(nm):1064±2，FWHM(nm):30±2，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP1550-50 | CWL(nm):1550±5，FWHM(nm):50±5，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP1550-100 | CWL(nm):1550±10，FWHM(nm):100±10，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating | |
| BP1550-150 | CWL(nm):1550±10，FWHM(nm):150±10，Tpeak >85%，Blocking range:200-1200 @ OD4，size:D12mm/D25mm/Custom | Hard coating |