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Bandpass Filter

Applications involving wireless receivers and transmitters typically use bandpass filters. The primary purpose of these filters is to minimize the bandwidth of the output signal to the band allocated to the transmittance. This limitation stops the transmitter from interfering with other stations.

Our UV Bandpass Filters deliver precise transmission of specific UV spectral bands while blocking out-of-band signals at higher and lower wavelengths. The multi-edge bandpass filters transmit wavelengths defined by a nominal center wavelength (CWL) and bandwidth (FWHM – Full-Width Half Max) while reflecting shorter and longer wavelengths. Also known as thin film or interference filters, these UV Bandpass filters use multi-layer hard coatings that provide durable performance without fading or aging in high output luminaires.

The UV range extends from 200 – 400nm, below the human vision range, and in susceptibility of UV-optimized silicon detectors. As a result, many applications’ valuable spectral signatures in the UV region are quickly evaluated using precisely positioned bandpass filters.

Visible light extends from 400-700nm within the typical responsivity of cost-effective silicon (Si) detectors. As a result, many applications have key spectral signatures that can be differentiated and evaluated using detailed narrow-band visible bandpass filters.

Near-infrared light extends from 700-2000nm, beyond human vision but still within the usual responsivity of silicon (Si) detectors. Many applications involving human tissue, materials, liquids, and gases have valuable spectral signatures in the near infrared that allow evaluation using precisely positioned bandpass filters.

Remote sensing is an application of spectral imaging widely used to analyze large areas from aircraft, unmanned vehicles, and satellite-based sensors. These measurements are then frequently correlated with ground-based measurements. Visible and infrared spectral bands’ common uses include monitoring natural and artificial features for agriculture, geology, and specialized applications.

Agriculture uses remote sensing to improve crop yields, monitor forest canopy, and measure crop health. Chlorophyll absorbs visible light and reflects near-infrared light, so evaluating specific spectral bands can help classify vegetation types, discriminate crop stress and moisture content, and monitor invasive species. Wide and narrow-band visible, the “red edge” transition from absorption to reflection and near-infrared spectral bands are particularly interesting for vegetation.

Geological features, including vegetation, minerals, bodies of water, roads, and buildings, can be differentiated with remote sensing. The deep blue end of the visible spectrum penetrates water best, though it is absorbed mainly through the atmosphere – helpful for underwater depth measurements or bathymetry and atmospheric correction calculations.

Remote sensing applications are rapidly growing with the improved availability, frequency, and cost of satellite and aerial data. The rise of unmanned aerial vehicles (UAVs) makes custom remote sensing data more accessible than ever, creating a new demand for application-specific sensors and cameras.

Salvo provides standard filters consistent with common remote sensing and satellite spectral bands – available now configured to your specific shape at

OEM filters for custom spectral bands, specs, production quantities, and shapes are also available. Salvo Technologies’ uses its exclusive micro-patterning technology to deliver application-specific sensors and focal plane arrays for remote sensing.

A medical expert’s trained eye can use the most delicate details to make an accurate diagnosis but imagine what else might be tapped through multispectral imaging. SpectroCam Multispectral Cameras provide video-rate imaging on a large or small scale in the narrow-band visible, NIR / SWIR (Near-InfraRed, Short Wave InfraRed), and UV (UltraViolet) wavelengths to reveal more – like fluorescence, spectral signatures & optical markers, and subcutaneous features.

Fluorescence imaging and sensing have many practical applications, including biological detectors, immunofluorescence, microscopy, labeling, chemical sensors, and whole animal/tissue imaging. Fluorophores are commonly attached to other molecules such as antibodies, proteins, amino acids, and peptides and used as probes to label a specific target. These fluorescent probes are then detected using a plate reader, small animal imaging system, fluorescence microscope, flow cytometer, or other fluorescence-reading instruments.

A fluorophore absorbs light at its excitation wavelength and typically emits light at a longer wavelength. Fluorophores or reactive fluorescent dyes are available from many sources to fit your application – with various reactive groups to attach to different functional groups within the target molecules. For the table of common fluorophores below, PIXELTEQ provides filters that selectively transmit the emitted wavelength and block the excitation wavelength – creating improved contrast for both sensing and imaging these fluorophores.

Label-free tissue sensing and imaging avoid labels commonly required in fluorescence and other techniques – providing practical, economical, and technical advantages in many applications. Various states of tissue frequently have different spectral characteristics.

A typical example is measuring the oxygenation level of hemoglobin – which can be saturated with oxygen molecules (oxyhemoglobin or “oxy”) or desaturated (deoxyhemoglobin or “deoxy”). Numerous medical devices and instruments evaluate results at multiple wavelengths to provide measurement and feedback on oxygenation levels.

Staining is another frequently used method in vivo and in vitro to highlight structures in biological tissues – such as classifying cell populations and defining muscle fibers or cytological structures. Biological staining is also used to flag proteins or nucleic acids and to mark cells in flow cytometry.

Salvo Technologies provides custom OEM filters that measure application-specific spectral bands for label-free and stained tissue imaging & sensing.

Clinical multispectral applications are rapidly growing, using Indocyanine Green (ICG) as a fluorophore that is FDA approved and administered orally to humans and research animals. A current application is the visualization of blood flow within the retina, with clinical use expanding into other areas where monitoring circulation is beneficial.

Emerging Applications

Other Biomedical Bandpass Filter Applications:

  • Blood vessel imaging during or after surgery
  • Hepatic function studies
  • Wound healing
  • Perfusion after transplantation or amputation
  • Angiograms track blood flow within the heart

Salvo Technologies provides standard ICG emission filters available now configured to shape.

OEM filters for ICG and other fluorophores, spectral specs, production quantities, shapes, and custom optics are also available. Application-specific sensors and cameras can overlay visible, ICG, and/or other near-infrared spectral bands. Request a consultation or quote now.

Contact Us


  • Video-rate multispectral imaging
  • Non-invasive & minimally invasive diagnostics
  • Biometrics
  • UV, Visible, and NIR macro & microimaging
  • ICG fluorescence & biomarkers
  • Retinal & fundus imaging
  • Tissue analysis
  • Erythema, wound, and burn evaluation
  • Vascular imaging & oxygenation analysis
  • Skin cancer screening & oncology research
  • Endoscope narrow-band imaging
  • Label-free detection
  • Optical readers & sorting
  • In-vivo animal imaging
  • Research tool

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