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IR Bandpass Filters: 1750 nm - 6000 nm Central Wavelength
Transmission Direction Indicator
The bandpass filters shown on this page feature center wavelengths from 1.75 to 6.00 µm. Transmission curves for individual filters are available by viewing the Transmission Data link for each filter on the Specs tab. Each filter is epoxied into a black anodized aluminum ring with an outer diameter of Ø1" and maximum edge thickness of 6.1 mm, which is compatible with our SM1 Lens Tubes. These filters feature a longer total lifetime than our UV, Visible, and NIR bandpass filters because they are fabricated from a single coated substrate. This fabrication technique also allows the unmounted filters to be used without resulting damage; however, the blocking transmission may be affected. As these filters cannot be removed from their mounts after purchase, please contact Tech Support to custom order unmounted filters.
Thorlabs' bandpass filters provide one of the simplest ways to transmit a well-defined wavelength band of light, while rejecting other unwanted radiation. Their design is essentially that of a thin film Fabry-Perot Interferometer formed by vacuum deposition techniques and consists of two reflecting stacks, separated by an even-order spacer layer. These reflecting stacks are constructed from alternating layers of high and low refractive index materials, which can have a reflectance in excess of 99.99%. By varying the thickness of the spacer layer and/or the number of reflecting layers, the central wavelength and bandwidth of the filter can be altered.
Each filter is housed in a black anodized aluminum ring that is labeled with an arrow indicating the design propagation direction. The ring makes handling easier and enhances the blocking OD by limiting scattering. These filters can be mounted in our extensive line of filter mounts and wheels. As the mounts are not threaded, Ø1" retaining rings will be required to mount the filters in one of our internally-threaded SM1 lens tubes.