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ND Filters: Mounted, AR Coated for 650 - 1050 nm
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One of Our Grinding Machines That is Used to Manufacture ND Filters
Thorlabs is pleased to offer its most popular mounted absorptive neutral density filters with a broadband antireflection coating for the 650 - 1050 nm range deposited on both surfaces. The high-performance, multilayer broadband B coating deposited on each filter is designed to minimize surface reflections within the 650 - 1050 nm range, thereby reducing the amount of stray light present. These coatings provide an average reflectance that is less than 0.5% over the specified wavelength range when light is normally incident on the filter surface. Typical transmission data may be found by clicking on the blue info icons () in the tables below.
These filters are mounted in engraved SM1L03 Ø1" lens tubes, which are compatible with a wide range of rigid optomechanical parts such as our cage systems and lens tubes. If desired, a mounted filter can be removed from its housing by unscrewing the retaining ring that secures the filter to the mount. Thorlabs offers a range of spanner wrenches that are an ideal match to these retaining rings. These filters are also available unmounted. The equivalent unmounted filter is listed in the drawing for each mounted filter, accessible through the red docs icons () below. Please see the Selection Guide table to the right for all neutral density filter options.
Unlike metallic neutral density filters, each absorptive ND filter is fabricated from one member of a family of Schott glasses (see the Specs tab for more information). Each Schott glass has a spectrally flat absorption coefficient. By varying the type of glass used and the thickness of that glass, we are able to produce our entire line of absorptive ND filters from just four types of Schott glass. See below for detailed information about the average transmission obtained with each of our AR-coated absorptive neutral density filters.
Optical Density and Transmission
where T is a value between 0 and 1. Choosing an ND filter with a higher optical density will translate to lower transmission and greater absorption of the incident light. For higher transmission and less absorption, a lower optical density would be appropriate. As an example, if a filter with an OD of 2 results in a transmission value of 0.01, this means the filter attenuates the beam to 1% of the incident power. Please note that the transmission data for our neutral density filters is provided in percent (%).
Please note that these products are not designed for use as laser safety equipment. For lab safety, Thorlabs offers an extensive line of safety and blackout products, including beam blocks, that significantly reduce exposure to stray light.