ND Filters: Unmounted, AR Coated for 350 - 700 nm
- Ø1/2" and Ø25 mm Versions Available
- Optical Densities Ranging from 0.1 to 6.0
- Ideal for Low-Power Applications (<1 W)
NE505B-A Mounted in LMR05
|Neutral Density Filter Selection Guide|
(400 - 650 nm)
(1000 - 2600 nm)
(350 - 700 nm)
(650 - 1050 nm)
(1050 - 1700 nm)
|UV Fused Silica
(200 - 1200 nm)
(350 - 1100 nm)
(2 - 16 µm)
|Wedged UVFS (200 - 1200 nm)|
|Wedged N-BK7 (350 - 1100 nm)|
|Wedged ZnSe (2 - 16 µm)|
|Neutral Density Filter Kits|
Click to Enlarge
One of Our Electron Beam Deposition Chambers that is Used to Coat Neutral Density Filters
- Attenuate Light in the Visible (350 - 700 nm AR Coating)
- Optical Densities at 633 nm Prior to Coating from 0.1 to 6.0
- Unmounted Ø1/2" and Ø25 mm Versions
- AR Coated to Reduce Back Reflections in an Optical System
- Ideal for Low-Power Applications (<1 Watt)
Thorlabs is pleased to offer its most popular unmounted absorptive neutral density filters with a broadband antireflection coating for the 350 - 700 nm range deposited on both surfaces. These filters are also available in mounted versions or with a broadband AR coating for the 650 - 1050 nm range. Please see the Selection Guide to the right for more information.
The high-performance, multilayer broadband A coating deposited on each filter is designed to minimize surface reflections within the 350 - 700 nm range, thereby reducing the amount of stray light present. These coatings provide an average reflectance that is less than 0.5% per surface over the specified wavelength range when light is normally incident on the filter surface. Typical transmission data is shown by clicking on the blue info icons () in the tables below.
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
Optical density (OD) indicates the attenuation factor provided by an optical filter, i.e. how much it reduces the optical power of an incident beam. OD is related to the transmission, T, by the equation
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.
|Diameter||12.7 mm||25.0 mm|
|Diameter Tolerance||+0.00 / -0.25 mm|
|Clear Aperture||>90% Outer Diameter|
|AR Coating Range||350 - 700 nm|
|Reflectance (Average)||<0.5% per Surfacea|
|Transmitted Wavefront Error
(OD < 1.3)
|<λ/4 (@ 633 nm)|
(OD ≥ 1.3)
|Surface Quality||40-20 Scratch-Dig|
|Parallelism||<3 arcmin (OD = 0.7, 0.8, 0.9, or 1.5);
3 arcmin (All Other ODs)
|<10 arcsec (OD = 0.7, 0.8, 0.9, or 1.5)
10 arcsec (All Other ODs)
The shaded regions in the graphs below denote the wavelength range for which the AR coating performance is specified. Click here to download optical density and transmission data. For the transmission and optical density of a particular filter, please click in the row corresponding to the filter in the tables below.