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ND Filters: Mounted, AR Coated for 350 - 700 nm


  • Mounted Ø25 mm Round Filter
  • Optical Densities Ranging from 0.1 to 6.0
  • Ideal for Low-Power Applications (<1 W)

NE20A-A

NE50A-A

NE05A-A Mounted
in a DET36A2 Detector

Application Idea

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ND Filter Manufacturing
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ND Filters Being Ground at Our Optics Manufacturing Facility

Features

  • Attenuate Light in the Visible (350 - 700 nm AR Coating)
  • Optical Densities Ranging from 0.1 to 6.0
  • Mounted Ø25 mm Round Filters
  • AR Coated to Reduce Back Reflections in an Optical System
  • Ideal for Low-Power Applications (<1 Watt)
  • Engraved with Coating Range and Part Number

Thorlabs is pleased to offer its most popular mounted absorptive neutral density filters with a broadband antireflection coating for the 350 - 700 nm range deposited on both surfaces. 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. These filters are also available in unmounted 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 filter transmission data is available by clicking on the 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 Thickness
0.1NG110.6 mm
0.2NG111.4 mm
0.3NG112.3 mm
0.4NG40.7 mm
0.5NG40.9 mm
0.6NG41.1 mm
1.0NG41.9 mm
1.3NG42.5 mm
2.0NG91.4 mm
3.0NG92.1 mm
4.0NG92.8 mm
5.0NG93.6 mm
6.0NG11.5 mm
General Specifications
Diameter 12.7 mm25.0 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 Quality40-20 Scratch-Dig
Parallelism3 arcmin10 arcsec

*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.

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

A AR Coating
Click to Enlarge

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

Posted Comments:
Aeckford  (posted 2014-09-25 15:39:56.333)
Why dont these have a slight angle on them to improve performance in stacked usage?
besembeson  (posted 2014-10-09 02:13:21.0)
Response from Bweh at Thorlabs. I believe you are concerned about interference effects due to reflections from multiple parallel surfaces in your application? We are designing new wedged reflective ND filters to eliminate such effects. If your need is immediate, we can apply a reflective ND coating (with appropriate OD) on a wedged window as a special.
jlow  (posted 2012-12-11 16:32:00.0)
Response from Jeremy at Thorlabs: Thank you for pointing this error out to us. We will rescan this and put the correct version up on the website.
rschoeneck  (posted 2012-12-07 11:10:58.287)
The transmission graph and raw data listed for the NE05A-A OD 0.5 ND filter show values that match an OD 0.3 filter. Probably the wrong element was used to generate the OD 0.5 transmission curve.

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

Item # Transmission Dataa ODb Thicknessc
NE01A-A info 0.1 0.6 mm
NE02A-A info 0.2 1.4 mm
NE03A-A info 0.3 2.3 mm
NE04A-A info 0.4 0.7 mm
NE05A-A info 0.5 0.9 mm
NE06A-A info 0.6 1.1 mm
NE10A-A info 1.0 1.9 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.
Item # Transmission Dataa ODb Thicknessc
NE13A-A info 1.3 2.5 mm
NE20A-A info 2.0 1.4 mm
NE30A-A info 3.0 2.1 mm
NE40A-A info 4.0 2.8 mm
NE50A-A info 5.0 3.6 mm
NE60A-A info 6.0 1.5 mm
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
NE01A-A Support Documentation
NE01A-AØ25 mm AR-Coated Absorptive Neutral Density Filter, SM1-Threaded Mount, 350-700 nm, OD: 0.1
$76.83
Today
NE02A-A Support Documentation
NE02A-AØ25 mm AR-Coated Absorptive Neutral Density Filter, SM1-Threaded Mount, 350-700 nm, OD: 0.2
$76.83
Today
NE03A-A Support Documentation
NE03A-AØ25 mm AR-Coated Absorptive Neutral Density Filter, SM1-Threaded Mount, 350-700 nm, OD: 0.3
$79.27
Today
NE04A-A Support Documentation
NE04A-AØ25 mm AR-Coated Absorptive Neutral Density Filter, SM1-Threaded Mount, 350-700 nm, OD: 0.4
$76.83
Today
NE05A-A Support Documentation
NE05A-AØ25 mm AR-Coated Absorptive Neutral Density Filter, SM1-Threaded Mount, 350-700 nm, OD: 0.5
$76.83
Today
NE06A-A Support Documentation
NE06A-AØ25 mm AR-Coated Absorptive Neutral Density Filter, SM1-Threaded Mount, 350-700 nm, OD: 0.6
$76.83
Today
NE10A-A Support Documentation
NE10A-AØ25 mm AR-Coated Absorptive Neutral Density Filter, SM1-Threaded Mount, 350-700 nm, OD: 1.0
$79.27
Today
NE13A-A Support Documentation
NE13A-AØ25 mm AR-Coated Absorptive Neutral Density Filter, SM1-Threaded Mount, 350-700 nm, OD: 1.3
$76.83
Today
NE20A-A Support Documentation
NE20A-AØ25 mm AR-Coated Absorptive Neutral Density Filter, SM1-Threaded Mount, 350-700 nm, OD: 2.0
$79.27
Today
NE30A-A Support Documentation
NE30A-AØ25 mm AR-Coated Absorptive Neutral Density Filter, SM1-Threaded Mount, 350-700 nm, OD: 3.0
$76.83
Today
NE40A-A Support Documentation
NE40A-AØ25 mm AR-Coated Absorptive Neutral Density Filter, SM1-Threaded Mount, 350-700 nm, OD: 4.0
$76.83
Today
NE50A-A Support Documentation
NE50A-AØ25 mm AR-Coated Absorptive Neutral Density Filter, SM1-Threaded Mount, 350-700 nm, OD: 5.0
$76.83
Today
NE60A-A Support Documentation
NE60A-AØ25 mm AR-Coated Absorptive Neutral Density Filter, SM1-Threaded Mount, 350-700 nm, OD: 6.0
$76.83
Today
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