ND Filters: Unmounted, AR Coated for 350

Overview
Specs
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Neutral Density Filter Selection Guide
Neutral Density Filter Selection Guide		Absorptive
Uncoated (400 - 650 nm)	Mounted
Uncoated (400 - 650 nm)	Unmounted
Uncoated (1000 - 2600 nm)	Mounted
Uncoated (1000 - 2600 nm)	Unmounted
AR Coated (350 - 700 nm)	Mounted
AR Coated (350 - 700 nm)	Unmounted
AR Coated (650 - 1050 nm)	Mounted
AR Coated (650 - 1050 nm)	Unmounted
AR Coated (1050 - 1700 nm)	Mounted
AR Coated (1050 - 1700 nm)	Unmounted
Variable
Reflective
UV Fused Silica (200 - 1200 nm)	Mounted
UV Fused Silica (200 - 1200 nm)	Unmounted
N-BK7 (350 - 1100 nm)	Mounted
N-BK7 (350 - 1100 nm)	Unmounted
ZnSe (2 - 16 µm)	Mounted
ZnSe (2 - 16 µm)	Unmounted
Wedged UVFS (200 - 1200 nm)
Wedged N-BK7 (350 - 1100 nm)
Variable
Neutral Density Filter Kits

Click to Enlarge
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 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

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 (%).

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.

Click to Enlarge

Transmission and Optical Density of -A Coated ND Filters. The values in the legend are the typical optical densities at 633 nm for each optic prior to coating. The blue shaded region indicates the wavelength range for which the AR coating performance is specified.

Optical Density (OD)^a	OD Tolerance^a	Substrate	Substrate Thickness^b	Ø1/2" Item #	Ø25 mm Item #
0.1	±0.005	NG11	0.6 mm	NE501B-A	NE01B-B
0.2	±0.01	NG11	1.4 mm	NE502B-A	NE02B-B
0.3	±0.015	NG11	2.3 mm	NE503B-A	NE03B-B
0.4	±0.02	NG4	0.7 mm	NE504B-A	NE04B-B
0.5	±0.025	NG4	0.9 mm	NE505B-A	NE05B-B
0.6	±0.03	NG4	1.1 mm	NE506B-A	NE06B-B
0.7	±0.04	NG4	1.3 mm	NE507B-A	NE07B-B
0.8	±0.05	NG4	1.5 mm	NE508B-A	NE08B-B
0.9	±0.05	NG4	1.7 mm	NE509B-A	NE09B-B
1.0	±0.05	NG4	1.9 mm	NE510B-A	NE10B-B
1.3	±0.065	NG4	2.5 mm	NE513B-A	NE13B-B
1.5	±0.08	NG4	2.9 mm	NE515B-A	NE15B-B
2.0	±0.1	NG9	1.4 mm	NE520B-A	NE20B-B
3.0	±0.15	NG9	2.1 mm	NE530B-A	NE30B-B
4.0	±0.2	NG9	2.8 mm	NE540B-A	NE40B-B
5.0	±0.25	NG9	3.6 mm	NE550B-A	NE50B-B
6.0	±0.3	NG1	1.5 mm	NE560B-A	NE60B-B

Measured at 633 nm before the AR coating is applied. See the tables below for a plot of typical transmission for each filter.
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	+0.00 / -0.25 mm
Clear Aperture	>90% Outer Diameter
AR Coating Range	350 - 700 nm
Reflectance (Average)	<0.5% per Surface^a
Surface Flatness^b	<λ/4 (OD = 0.7, 0.8, 0.9, or 1.5) λ/4 (All Other ODs)
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)

At 0° AOI
At 633 nm

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.

Click to Enlarge

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:

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 #	OD at 633 nm^b	Thickness^c
NE510B-A	1.0 ± 0.05	1.9 mm
NE513B-A	1.3 ± 0.065	2.5 mm
NE515B-A	1.5 ± 0.08	2.9 mm
NE520B-A	2.0 ± 0.1	1.4 mm
NE530B-A	3.0 ± 0.15	2.1 mm
NE540B-A	4.0 ± 0.2	2.8 mm
NE550B-A	5.0 ± 0.25	3.6 mm
NE560B-A	6.0 ± 0.3	1.5 mm

Item #	OD at 633 nm^b	Thickness^c
NE501B-A	0.1 ± 0.005	0.6 mm
NE502B-A	0.2 ± 0.01	1.4 mm
NE503B-A	0.3 ± 0.015	2.3 mm
NE504B-A	0.4 ± 0.02	0.7 mm
NE505B-A	0.5 ± 0.025	0.9 mm
NE506B-A	0.6 ± 0.03	1.1 mm
NE507B-A	0.7 ± 0.04	1.3 mm
NE508B-A	0.8 ± 0.05	1.5 mm
NE509B-A	0.9 ± 0.05	1.7 mm

Click the icon to view a plot of the typical filter transmission.
Measured before the AR coating is applied. See Transmission Data graphs for typical performance.
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 Ø1/2" Neutral Density Filter, AR Coated: 350-700 nm, OD: 0.1

$39.23

Today

NE502B-A Ø1/2" Neutral Density Filter, AR Coated: 350-700 nm, OD: 0.2

$39.23

Today

NE503B-A Ø1/2" Neutral Density Filter, AR Coated: 350-700 nm, OD: 0.3

$39.23

Today

NE504B-A Ø1/2" Neutral Density Filter, AR Coated: 350-700 nm, OD: 0.4

$39.23

Today

NE505B-A Ø1/2" Neutral Density Filter, AR Coated: 350-700 nm, OD: 0.5

$39.23

Today

NE506B-A Ø1/2" Neutral Density Filter, AR Coated: 350-700 nm, OD: 0.6

$39.23

Today

NE507B-A Ø1/2" Neutral Density Filter, AR Coated: 350-700 nm, OD: 0.7

$39.23

Today

NE508B-A Ø1/2" Neutral Density Filter, AR Coated: 350-700 nm, OD: 0.8

$39.23

Today

NE509B-A Ø1/2" Neutral Density Filter, AR Coated: 350-700 nm, OD: 0.9

$39.23

Today

NE510B-A Ø1/2" Neutral Density Filter, AR Coated: 350-700 nm, OD: 1.0

$39.23

Today

NE513B-A Ø1/2" Neutral Density Filter, AR Coated: 350-700 nm, OD: 1.3

$39.23

Today

NE515B-A Ø1/2" Neutral Density Filter, AR Coated: 350-700 nm, OD: 1.5

$39.23

Today

NE520B-A Ø1/2" Neutral Density Filter, AR Coated: 350-700 nm, OD: 2.0

$39.23

Today

NE530B-A Ø1/2" Neutral Density Filter, AR Coated: 350-700 nm, OD: 3.0

$39.23

Today

NE540B-A Ø1/2" Neutral Density Filter, AR Coated: 350-700 nm, OD: 4.0

$39.23

Today

NE550B-A Ø1/2" Neutral Density Filter, AR Coated: 350-700 nm, OD: 5.0

$39.23

Today

NE560B-A Ø1/2" Neutral Density Filter, AR Coated: 350-700 nm, OD: 6.0

$39.23

5-8 Days

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

Item #	OD at 633 nm^b	Thickness^c
NE10B-A	1.0 ± 0.05	1.9 mm
NE13B-A	1.3 ± 0.065	2.5 mm
NE15B-A	1.5 ± 0.08	2.9 mm
NE20B-A	2.0 ± 0.1	1.4 mm
NE30B-A	3.0 ± 0.15	2.1 mm
NE40B-A	4.0 ± 0.2	2.8 mm
NE50B-A	5.0 ± 0.25	3.6 mm
NE60B-A	6.0 ± 0.3	1.5 mm

Item #	OD at 633 nm^b	Thickness^b
NE01B-A	0.1 ± 0.005	0.6 mm
NE02B-A	0.2 ± 0.01	1.4 mm
NE03B-A	0.3 ± 0.015	2.3 mm
NE04B-A	0.4 ± 0.02	0.7 mm
NE05B-A	0.5 ± 0.025	0.9 mm
NE06B-A	0.6 ± 0.03	1.1 mm
NE07B-A	0.7 ± 0.04	1.3 mm
NE08B-A	0.8 ± 0.05	1.5 mm
NE09B-A	0.9 ± 0.05	1.7 mm

Click the icon to view a plot of the typical filter transmission.
Measured before the AR coating is applied. See Transmission Data graphs for typical performance.
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 Ø25 mm Neutral Density Filter, AR Coated: 350-700 nm, OD: 0.1

$62.76

5-8 Days

NE02B-A Ø25 mm Neutral Density Filter, AR Coated: 350-700 nm, OD: 0.2

$62.76

Lead Time

NE03B-A Ø25 mm Neutral Density Filter, AR Coated: 350-700 nm, OD: 0.3

$60.34

5-8 Days

NE04B-A Ø25 mm Neutral Density Filter, AR Coated: 350-700 nm, OD: 0.4

$62.76

Today

NE05B-A Ø25 mm Neutral Density Filter, AR Coated: 350-700 nm, OD: 0.5

$62.76

Today

NE06B-A Ø25 mm Neutral Density Filter, AR Coated: 350-700 nm, OD: 0.6

$62.76

5-8 Days

NE07B-A Ø25 mm Neutral Density Filter, AR Coated: 350-700 nm, OD: 0.7

$62.76

Today

NE08B-A Ø25 mm Neutral Density Filter, AR Coated: 350-700 nm, OD: 0.8

$62.76

Today

NE09B-A Ø25 mm Neutral Density Filter, AR Coated: 350-700 nm, OD: 0.9

$62.76

Today

NE10B-A Ø25 mm Neutral Density Filter, AR Coated: 350-700 nm, OD: 1.0

$60.34

5-8 Days

NE13B-A Ø25 mm Neutral Density Filter, AR Coated: 350-700 nm, OD: 1.3

$62.76

Today

NE15B-A Ø25 mm Neutral Density Filter, AR Coated: 350-700 nm, OD: 1.5

$62.76

Today

NE20B-A Ø25 mm Neutral Density Filter, AR Coated: 350-700 nm, OD: 2.0

$60.34

Lead Time

NE30B-A Ø25 mm Neutral Density Filter, AR Coated: 350-700 nm, OD: 3.0

$62.76

Lead Time

NE40B-A Ø25 mm Neutral Density Filter, AR Coated: 350-700 nm, OD: 4.0

$62.76

Today

NE50B-A Ø25 mm Neutral Density Filter, AR Coated: 350-700 nm, OD: 5.0

$62.76

Today

NE60B-A Ø25 mm Neutral Density Filter, AR Coated: 350-700 nm, OD: 6.0

$62.76

Today

View All »Matching Part Numbers

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

Features

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

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