Bandpass Filter Kits

- Visible Kit, 10 nm Bandpass: 10 Center Wavelengths from 351 to 800 nm
- Visible Kit, 40 nm Bandpass: 10 Center Wavelengths from 400 to 850 nm
- IR Kit, 10 - 12 nm Bandpass: 10 Center Wavelengths from 850 to 1600 nm
FKBIR10
IR Filter Kit
10-12 nm FWHM
CWL = 600 nm
FWHM = 40 nm
CWL = 1100 nm
FWHM = 10 nm
CWL = 700 nm
FWHM = 10 nm
FKBV40
Visible Filter Kit
40 nm FWHM

Please Wait

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Our hard-coated bandpass filter
engraving and transmission is shown above.
Please note that the transmission direction only affects backscatter and reflection, not filter performance.
Features
- Visible Bandpass Filter Kits
- Item # FKBV10: 351 to 800 nm Center Wavelengths, 10 nm FWHM
- Item # FKBV40: 400 to 850 nm Center Wavelengths, 40 nm FWHM
- IR Bandpass Filter Kit
- Item # FKBIR10: 850 to 1600 nm Center Wavelengths, 10 nm or 12 nm FWHM (Filter Dependent)
- Engraved Filter Mount with Ø25 mm Ring
Thorlabs' Bandpass Filter Kits each contain 10 mounted bandpass filters that can be used to transmit a well-defined wavelength band in the visible or IR, while rejecting other unwanted radiation. The bandpass filter kits include a selection of our Hard-Coated Bandpass Filters.
Our hard-coated bandpass filters provide higher transmission, steeper cut on and cut off slopes, greater blocking, and increased durability when compared to our line of soft-coated bandpass filters. The hard-coated filters are 3.5 mm thick, which allows the Ø25 mm filters to be used as drop-in replacements for our fluorescence emission filters.
Each filter is mounted in an unthreaded Ø25 mm ring that can be placed into our selection of Ø1" lens tubes and filter mounts using retaining rings, as shown to the left. The filter kits come in a convenient plastic box for storage and transportation purposes. Please see the Tutorial tab for more information about the structure of the hard-coated bandpass filters.
Thorlabs also offers a wide range of individually sold bandpass filters. To inquire about our custom bandpass filter options, including the possibility of alternative central wavelengths or bandwidths, please contact Tech Support. Please note that there is a significant lead time and tooling cost associated with custom filters that makes the purchase of only a few pieces fairly costly.
Additional Bandpass Filters | |||||
---|---|---|---|---|---|
UV/VIS/NIR Bandpass Filters 300 - 1650 nm CWLs |
IR Hard-Coated Bandpass Filters 1750 - 12000 nm CWLs |
UV/Visible Soft-Coated Bandpass Filters 340 - 694.3 nm CWLs |
NIR Soft-Coated Bandpass Filters 700 - 1610 nm CWLs |
Bandpass Filter Kits | |
We also offer custom bandpass filters with other central wavelengths or FWHM. To request a quote, contact Tech Support. |
General Specifications | |
---|---|
Kit Type | Hard-Coated Bandpass Filter Kits (Item #s FKBV10, FKBV40, and FKBIR10) |
Bandpass Filter Type | Premium Hard-Coated |
Out of Band Optical Density |
ODavg ≥ 4 (351 nm CWL) ODabs > 5 (CWLs ≥ 400 nm) |
Clear Aperture | Ø21.1 mm |
Thickness | 3.5 mm |
Surface Quality | 60-40 Scratch-Dig |
Coating | Hard Coated |
Operating Temperature |
-40 to 90 °Ca |
Edge Treatment | Mounted in Black Anodized Aluminum Ring |
Edge Markingsb | Item # |
Substrate(s) | UV Fused Silicac |
Damage Threshold | Not Specified |
Hard-Coated Bandpass Filter Structure

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The number of layers shown in this schematic is not indicative of the number of layers in an actual hard-coated bandpass filter. Also the drawing is not to scale.
A bandpass filter is created by depositing layers of material on the surface of the substrate. For our hard-coated bandpass filters, dielectric stacks alternating with dielectric spacer layers comprise the thin filter coating stack. Each dielectric stack is composed of a large number of alternating layers of low-index and high-index material. The thickness of each layer in the dielectric stack is λ/4, where λ is the central wavelength of the bandpass filter (i.e. the wavelength with the highest transmittance through the filter). The spacer layers are placed in between the stacks and have a thickness of (nλ)/2, where n is an integer. A Fabry-Perot cavity is formed by each spacer layer sandwiched between dielectric stacks. The filter is mounted in an engraved metal ring for protection and ease of handling.
Filter Operation Overview
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. However, the band of blocked wavelengths on either side of the central wavelength is small. To increase the blocking range of the filter, the substrate uses or has its spacer layers coated in materials with broad blocking ranges. Although these materials effectively block out-of-band transmission of incident radiation, they also decrease the transmission through the filter in the passband.
Filter Orientation
An engraved arrow on the edge of the filter is used to indicate the recommended direction for the transmission of light through the filter. Orienting the coated side toward the source will reduce unwanted scattering and minimize reflections sent back toward the source. Using the filter in the opposite orientation will not, however, significantly affect the performance of the filter. The plot to the bottom left was made by illuminating the filter with a low intensity broadband light and measuring the transmission as a function of wavelength. The plot shows that the transmission direction through the filter has very little effect on the intensity and the spectrum of the light transmitted through the filter. The minimal variation between the forward and backward traces is most likely due to a small shift in the incident angle of the light on the filter introduced when the filter was removed, flipped over, and replaced in the jig.
The filter is intended to be used with collimated light normally incident on the surface of the filter. For uncollimated light or light striking the surface at an angle not normally incident to the surface, the central wavelength (wavelength corresponding to peak transmission) will shift toward lower wavelengths and the shape of the transmission region (passband) will change. Varying the angle of incidence (AOI) by a small amount can be used to effectively tune the passband over a narrow range. Large changes in the incident angle will cause larger shifts in the central wavelength but will also significantly distort the shape of the passband and, more importantly, cause a significant decrease in the transmittance of the passband, as seen in the plot to the bottom right.

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This plot displays transmission forward and backward through the FBH800-10 Premium Bandpass Filter and the FBH800-40 Premium Bandpass Filter.

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This plot displays transmission through the FBH800-10 Premium Bandpass Filter at varying angles of incidence (AOI).
Posted Comments: | |
tebeech
 (posted 2014-03-05 04:53:36.227) Despite the fact that a filter wheel is displayed as a "related item" along the sidebar, the mounted bandpass filters are too thick to be mounted in such a device. Specifically, we purchased the visible bandpass filter kit FKB-VIS-10 and attempted to mount the filters in a FW1A. The thickness of the filters exceeds the thickness of the filter wheel mount and as such there is no way of affixing the filters in place. It is remarkable to me that a thorlabs filter cannot be mounted in a thorlabs filter wheel. Such basic must have been tested and as yet I am forced to purchase additional items to achieve basic functionality. jlow
 (posted 2014-03-05 10:48:15.0) Response from Jeremy at Thorlabs: I apologize for this mistake on our website. We have removed the thin filter wheels from the related items. To mount the filters to FW1A, you would need to get SM1L05. I will contact you directly about this. |


