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Bandpass Filters

Optical filters are used to select certain wavelengths within optical systems. Filters can be broad transmitting large wavelength ranges or very specific & targeted only to a few wavelengths. Bandpass Filters transmit a band of wavelengths while blocking the wavelengths on either side of that band. The opposite of a bandpass filter is a notch filter which blocks a specific band of wavelengths. Longpass filters transmit wavelengths longer than the specified cut-on wavelengths and block the shorter wavelengths. Shortpass filters are the opposite and transmit the shorter wavelengths. Optical glass filters are widely used in safety glasses, industrial measurement, regulation technology and environment protection.

Paralight Optics offers a diverse line-up of dielectric-coated spectral filters. Our hard-coated bandpass filters offer higher transmission and are more durable and longer-lasting than our soft-coated bandpass filters. The high-performance edgepass filters include both long- and short-pass options. Notch filters, also known as band-stop or band-rejection filters, are useful in applications where one needs to block light from a laser. We also offer dichroic mirrors and beamsplitters.

Interference bandpass filters are used to pass certain narrow wavelength bands with high transmission and block unwanted light. The pass band can be very narrow such as 10 nm or very wide depending on your specific application. Rejection bands are deeply blocked with OD from 3 to 5 or even more. Our line of interference bandpass filters covers wavelength ranges from the ultraviolet to near infrared, including many types of primary laser, biomedical and analytical spectral lines. The filters are mounted in black anodized metal rings.



Wavelength Ranges::

From the Ultraviolet to Near Infrared


Many types of primary laser, biomedical and analytical spectral lines

Pass Band:

Narrow or Wide depending on your specific needs

Rejection Bands:

OD from 3-5 or above


Common Specifications:


Our hard-coated bandpass filters is created by depositing layers of dielectric stacks alternating with dielectric spacer layers, a Fabry-Perot cavity is formed by each spacer layer sandwiched between dielectric stacks. The constructive interference conditions of a Fabry-Perot cavity allow light at the central wavelength, and a small band of wavelengths to either side, to be transmitted efficiently, while destructive interference prevents the light outside the passband from being transmitted. The filter is mounted in an engraved metal ring for protection and ease of handling.


Ranges & Tolerances

  • Type

    Interference Bandpass filter

  • Materials

    Glass in an Anodized Aluminum Ring

  • Mounting Dimension Tolerance


  • Thickness

    < 10 mm

  • CWL Tolerance

    ±2 nm

  • FWHM (Full width at half maximum)

    10 ± 2 nm

  • Peak Transmission

    > 45%

  • Block

    < 0.1% @ 200-1100 nm

  • CWL Shift

    < 0.02 nm/℃

  • Surface Quality (scratch-dig)

    80 - 50

  • Clear Aperture

    > 80%



◆ Reference transmission curve of Interference Bandpass Filter
◆ Paralight Optics offers different types of dielectric-coated spectral filters, e.g., hard-coated bandpass filters, soft-coated bandpass filters, high-performance edgepass filters which include both long pass filters and short pass filters, notch filters AKA band-stop or band-rejection filters, IR-blocking filters that reject light in the MIR ranges. We additionally offer dichroic color filters individually and as a set. For more details or to get a quote, feel free to contact us.