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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)

NE50B-A

(Ø25 mm)

NE520B-A

(Ø1/2")

Application Idea

NE505B-A Mounted in LMR05

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Optic Cleaning Tutorial

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One of Our Electron Beam Deposition Chambers That is Used to Coat Neutral Density Filters

Features

  • Attenuate Light in the Visible (350 - 700 nm AR Coating)
  • Optical Densities Ranging 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)
  • Edge Blackening Available Upon Request

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 reflectivity that is less than 0.5% over the specified wavelength range when light is normally incident on the filter surface. Typical transmission data is shown by clicking on the graph 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 (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

Optical Density 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 (%).

For lab safety, Thorlabs offers an extensive line of safety and blackout products that significantly reduces exposure to stray light.

Selection Guide for Neutral Density Filters
Absorptive Reflective
Uncoated
(400 - 650 nm)
Mounted N-BK7
(350 - 1100 nm)
Mounted
Unmounted Unmounted
Uncoated
(800 - 2600 nm)
Mounted UV Fused Silica
(200 - 1200 nm)
Mounted
Unmounted Unmounted
AR Coated
(350 - 700 nm)
Mounted ZnSe
(2 - 16 µm)
Mounted
Unmounted Unmounted
AR Coated
(650 - 1050 nm)
Mounted Wedged Reflective
Unmounted Variable Reflective
AR Coated
(1050 - 1700 nm)
Mounted Neutral Density Filter Kits
Unmounted
Optical DensitySubstrateSubstrate Thicknessa
0.1 NG11 0.6 mm
0.2 NG11 1.4 mm
0.3 NG11 2.3 mm
0.4 NG4 0.7 mm
0.5 NG4 0.9 mm
0.6 NG4 1.1 mm
1.0 NG4 1.9 mm
1.3 NG4 2.5 mm
2.0 NG9 1.4 mm
3.0 NG9 2.1 mm
4.0 NG9 2.8 mm
5.0 NG9 3.6 mm
6.0 NG1 1.5 mm
  • Values given are typical. The actual thickness of each ND filter is dependent on the optical density of the lot of glass used to manufacture each lot of ND filters.
General Specifications
Diameter 12.7 mm 25.0 mm
Diameter Tolerance +0.0 / -0.25 mm
Clear Aperture >90% Outer Diameter
Ravg (350 - 700 nm) <0.5%
Surface Flatness (@ 633 nm) λ/4
Surface Quality 40-20 Scratch-Dig
Parallelism 3 arcmin 10 arcsec

Click here to download optical density and transmission data.
For the transmission and optical density of a particular filter, please click More Info Icon in the row corresponding to the filter in the tables below.

The shaded regions in the graphs below denote the recommended wavelength range for these filters. Click here to download optical density and transmission data. For the transmission and optical density of a particular filter, please click More Info Icon in the row corresponding to the filter in the tables below.

A AR Coating
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Click Here for Raw Data
The blue shaded region indicates the specified 350 - 700 nm wavelength range for optimum performance.

Posted Comments:
n house  (posted 2019-04-16 18:55:24.933)
I recently purchased these unmounted AR-coated ND filters. Are the OD plots you show on your website the plots I should expect, or can the intensity of transmission change slightly from batch-to-batch?
YLohia  (posted 2019-04-17 09:08:16.0)
Hello, thank you for contacting Thorlabs. The plots shown on the website are typical, so there would be a slight batch-to-batch variation over the specified operating range. Since these are AR-coated, there may be more significant variations in the out-of-band regions between different batches.
gilliss  (posted 2017-02-22 12:26:04.373)
Looking at plots such as https://www.thorlabs.com/images/TabImages/ND_Filters_A-Coated_Optical_Density_All_780.gif and then https://www.thorlabs.com/images/TabImages/ND_Filters_A-Coated_Optical_Density_Rest_780.gif I'm confused as to why all of the features in ND2.0 filters and up seem to shift over by 50nm. Could this be a measurement error? By these plots, all filters below OD2.0 seem appropriate for the stated wavelength range of 350 to 700, but the higher ones seem to only be useful above 400  nm.
jlow  (posted 2017-03-01 04:46:47.0)
Response from Jeremy at Thorlabs: The reason there's a shift is because of the material used. The ND filters with OD2, 3, 4, and 5, are made from NG9 glass whereas the lower OD filters were made with NG4 or NG11 glass. You can see the type of glass used under the Specs tab.
michele.maiorano  (posted 2015-01-12 09:39:41.34)
Dear Sirs, I would like to buy about 30 unmounted and AR-coated absorptive ND filters for both visible and NIR light at different OD, but I need bigger sizes, i.e. 37.0 +0.0/-0.2 mm: could it be possible to make such an order? Thank you for your attention. Best regards, Michele Maiorano
besembeson  (posted 2015-01-13 06:36:05.0)
Response from Bweh at Thorlabs: Yes we do provide custom sizes for these ND filters. I will followup with you by email for your OD, AR coating specifications and quotation.

Ø1/2" Unmounted Absorptive ND Filters, AR-Coated: 350 - 700 nm

Item # Transmission Dataa ODb Thicknessc
NE510B-A info
1.0 1.9 mm
NE513B-A info 1.3 2.5 mm
NE520B-A info 2.0 1.4 mm
NE530B-A info 3.0 2.1 mm
NE540B-A info 4.0 2.8 mm
NE550B-A info 5.0 3.6 mm
NE560B-A info 6.0 1.5 mm
Item # Transmission Dataa ODb Thicknessc
NE501B-A info 0.1 0.6 mm
NE502B-A info 0.2 1.4 mm
NE503B-A info 0.3 2.3 mm
NE504B-A info 0.4 0.7 mm
NE505B-A info 0.5 0.9 mm
NE506B-A info 0.6 1.1 mm
  • The shaded region in the popup graphs denotes the wavelength range of the AR coating.
  • Measured at 633 nm.
  • Values given are typical. The actual thickness of each ND filter is dependent on the optical density of the lot of glass used to manufacture each lot of ND filters.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
NE501B-A Support Documentation
NE501B-AØ1/2" AR-Coated Neutral Density Filter, 350-700 nm, OD: 0.1
$38.09
Today
NE502B-A Support Documentation
NE502B-AØ1/2" AR-Coated Neutral Density Filter, 350-700 nm, OD: 0.2
$38.09
Today
NE503B-A Support Documentation
NE503B-AØ1/2" AR-Coated Neutral Density Filter, 350-700 nm, OD: 0.3
$38.09
Today
NE504B-A Support Documentation
NE504B-AØ1/2" AR-Coated Neutral Density Filter, 350-700 nm, OD: 0.4
$38.09
Today
NE505B-A Support Documentation
NE505B-AØ1/2" AR-Coated Neutral Density Filter, 350-700 nm, OD: 0.5
$38.09
Today
NE506B-A Support Documentation
NE506B-AØ1/2" AR-Coated Neutral Density Filter, 350-700 nm, OD: 0.6
$38.09
Today
NE510B-A Support Documentation
NE510B-AØ1/2" AR-Coated Neutral Density Filter, 350-700 nm, OD: 1.0
$38.09
Today
NE513B-A Support Documentation
NE513B-AØ1/2" AR-Coated Neutral Density Filter, 350-700 nm, OD: 1.3
$38.09
Today
NE520B-A Support Documentation
NE520B-AØ1/2" AR-Coated Neutral Density Filter, 350-700 nm, OD: 2.0
$38.09
Today
NE530B-A Support Documentation
NE530B-AØ1/2" AR-Coated Neutral Density Filter, 350-700 nm, OD: 3.0
$38.09
Today
NE540B-A Support Documentation
NE540B-AØ1/2" AR-Coated Neutral Density Filter, 350-700 nm, OD: 4.0
$38.09
Today
NE550B-A Support Documentation
NE550B-AØ1/2" AR-Coated Neutral Density Filter, 350-700 nm, OD: 5.0
$38.09
Today
NE560B-A Support Documentation
NE560B-AØ1/2" AR-Coated Neutral Density Filter, 350-700 nm, OD: 6.0
$38.09
Today

Ø25 mm Unmounted Absorptive ND Filters, AR-Coated: 350 - 700 nm

Item # Transmission Dataa ODb Thicknessc
NE10B-A info 1.0 1.9 mm
NE13B-A info 1.3 2.5 mm
NE20B-A info 2.0 1.4 mm
NE30B-A info 3.0 2.1 mm
NE40B-A info 4.0 2.8 mm
NE50B-A info 5.0 3.6 mm
NE60B-A info 6.0 1.5 mm
Item # Transmission Dataa ODb Thicknessc
NE01B-A info 0.1 0.6 mm
NE02B-A info
0.2 1.4 mm
NE03B-A info 0.3 2.3 mm
NE04B-A info 0.4 0.7 mm
NE05B-A info 0.5 0.9 mm
NE06B-A info 0.6 1.1 mm
  • The shaded region in the popup graphs denotes the wavelength range of the AR coating.
  • Measured at 633 nm.
  • Values given are typical. The actual thickness of each ND filter is dependent on the optical density of the lot of glass used to manufacture each lot of ND filters.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
NE01B-A Support Documentation
NE01B-AØ25 mm AR-Coated Neutral Density Filter, 350-700 nm, OD: 0.1
$60.93
Today
NE02B-A Support Documentation
NE02B-AØ25 mm AR-Coated Neutral Density Filter, 350-700 nm, OD: 0.2
$60.93
Today
NE03B-A Support Documentation
NE03B-AØ25 mm AR-Coated Neutral Density Filter, 350-700 nm, OD: 0.3
$58.58
Today
NE04B-A Support Documentation
NE04B-AØ25 mm AR-Coated Neutral Density Filter, 350-700 nm, OD: 0.4
$60.93
Today
NE05B-A Support Documentation
NE05B-AØ25 mm AR-Coated Neutral Density Filter, 350-700 nm, OD: 0.5
$60.93
Today
NE06B-A Support Documentation
NE06B-AØ25 mm AR-Coated Neutral Density Filter, 350-700 nm, OD: 0.6
$60.93
Today
NE10B-A Support Documentation
NE10B-AØ25 mm AR-Coated Neutral Density Filter, 350-700 nm, OD: 1.0
$58.58
Today
NE13B-A Support Documentation
NE13B-AØ25 mm AR-Coated Neutral Density Filter, 350-700 nm, OD: 1.3
$60.93
Today
NE20B-A Support Documentation
NE20B-AØ25 mm AR-Coated Neutral Density Filter, 350-700 nm, OD: 2.0
$58.58
Today
NE30B-A Support Documentation
NE30B-AØ25 mm AR-Coated Neutral Density Filter, 350-700 nm, OD: 3.0
$60.93
Today
NE40B-A Support Documentation
NE40B-AØ25 mm AR-Coated Neutral Density Filter, 350-700 nm, OD: 4.0
$60.93
Today
NE50B-A Support Documentation
NE50B-AØ25 mm AR-Coated Neutral Density Filter, 350-700 nm, OD: 5.0
$60.93
Today
NE60B-A Support Documentation
NE60B-AØ25 mm AR-Coated Neutral Density Filter, 350-700 nm, OD: 6.0
$60.93
Today
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