Bandpass Filters – Custom Specified

Product Description

Bandpass filters isolate a band of wavelengths from the total spectrum by providing a band of high transmission and bands of high rejection of spectral energy on both the long and short wavelength sides of the transmission band. These filters are defined by cut-on and cut-off slopes establishing the transition between high rejection and high transmission. Cut-on and cut-off edges defining the bandpass region can either be defined by Fabry-Perot construction, as is common for narrow bandpass filters, or by the combination of long wave and short wave pass filter coatings. Bandpass filters can be manufactured with a wide variety of performance attributes ranging from the simplest single-cavity, unblocked Fabry-Perot construction, to the more complex multi-cavity, fully-blocked, all-dielectric, single-substrate construction.

We make them all - from the simplest to the most complex, over the range of 200 nm to 8 µm with bandwidths as narrow as 0.1nm in the UV/VIS to as wide as 2µm in the mid-wave IR.

The majority of the bandpass filters that we manufacture are custom designed for OEM instrumentation such as clinical diagnostic analyzers, colorimeters for paint color process control, water analyzers, gas analyzers for air pollution monitoring, and many more. Working in partnership with the instrument manufacturer's optical engineers and scientists, we design custom bandpass filters that are optimized for the nuances of the instrument architecture and the analysis to be performed on it. This team approach enables delivery of the best cost / performance / time-to-market value to the instrument maker.

We make bandpass filters in several different configurations:

Single substrate, image quality, all-dielectric hard sputtered coating

Single substrate, general quality, all-dielectric hard sputtered coating

Single substrate, general quality, all-dielectric semi-hard e-beam evaporated coating

Multi-element, image quality, all-dielectric hard sputtered coating, laminated assembly

Multi-element, general quality, all-dielectric hard sputtered coating, laminated assembly

Multi-element, general quality, all-dielectric hard sputtered coating, mechanical assembly

Multi-element, image quality, semi-hard thermally evaporated coating, laminated assembly

Multi-element, general quality, semi-hard thermally evaporated coating, laminated assembly

All of these configurations can deliver exceptional performance at economical cost. For many applications, the single substrate configuration is the best choice, but for some of the most demanding applications where the absolute best signal-to-noise ratio possible is necessary, our multi-element - laminated or mechanical assembly configuration is the only choice that will guarantee optimum signal-to-noise ratio. We recommend the best configuration given the requirements of the instrument.

Bandpass Filter Specification Checklist

The list of parameters that follows includes the most common items used to specify a bandpass filter. Many of the parameters are general enough to apply to any optical filter. Care should always be taken to avoid over-specification. For example, specifying some of the specifications in the optical category such as transmitted wavefront error can, depending on the chosen value, have a significant impact on cost while providing no increase in filter performance if the filter is used in a photometric detection application. When using this checklist, the best strategy is to provide what is known to be important and allow our technical team to recommend other specifications from the list that will insure the best performance for the application. After completing the checklist, please call 508-528-4411 to speak directly to one of our Technical Sales Engineers, or email us at to address your specific requirements.

Bandpass Filter Specification Checklist

Operating Conditions
Operating Temperature
Storage Temperature
Angle of Incidence
System Speed
Illumination Source
Polarization State
Length / Length tolerance
Width / Width tolerance
Thickness / Thickness tolerance (or max)
Active Area (min)
Edge treatment-Bevel
Edge treatment-Ring
Surface Quality
Flatness (S1)
Flatness (S2)
Center wavelength
Bandwidth (FWHM)
Low half-power wavelength
High half-power wavelength
%Tavg range
Edge Steepness
BW@ 10% Tpk
BW@ 1.0% Tpk
BW@ 0.1% Tpk
BW@ 0.01% Tpk
BW@ 0.001% Tpk
Blocking range
Blocking (min OD / max %T over range)
Blocking, Integrated (S/N) Range of Transmittance