ND Filters: Mounted, AR Coated for 350

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Transmission and Optical Densities of -A Coated ND Filters. The values in the legends 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.

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. 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% 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.

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 below 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 (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

OD = log₁₀(1/T), or T = 10^-OD

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.

Click to Enlarge
ND Filters Being Ground at Our Optics Manufacturing Facility

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

Optical Density (OD)^a	OD Tolerance^a	Substrate	Substrate Thickness^b
0.1	±0.005	NG11	0.6 mm
0.2	±0.01	NG11	1.4 mm
0.3	±0.015	NG11	2.3 mm
0.4	±0.02	NG4	0.7 mm
0.5	±0.025	NG4	0.9 mm
0.6	±0.03	NG4	1.1 mm
0.7	±0.04	NG4	1.3 mm
0.8	±0.05	NG4	1.5 mm
0.9	±0.05	NG4	1.7 mm
1.0	±0.05	NG4	1.9 mm
1.3	±0.065	NG4	2.5 mm
1.5	±0.08	NG4	2.9 mm
2.0	±0.1	NG9	1.4 mm
3.0	±0.15	NG9	2.1 mm
4.0	±0.2	NG9	2.8 mm
5.0	±0.25	NG9	3.6 mm
6.0	±0.3	NG1	1.5 mm

Measured at 633 nm before the AR coating was applied.
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	25.0 mm
Diameter Tolerance	+0.00 / -0.25 mm
Clear Aperture	>90% of Diameter
R_avg (350 - 700 nm)	<0.5%
Surface Flatness (@ 633 nm)	<λ/4 (OD = 0.7, 0.8, 0.9, or 1.5) λ/4 (All Other ODs)
Surface Quality	40-20 Scratch-Dig
Parallelism	<10 arcsec

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:

Ju Fe (posted 2020-10-12 10:50:58.603)

Hello Thorlabs, In the excel files, a message says "Slight variations in performance data will occur from lot to lot". Could you estimate the uncertainty on the transmission curves ? Best Regards, Julien

asundararaj (posted 2020-10-26 04:16:00.0)

Thank you for contacting Thorlabs. The variation in the performance is a result of the tolerance on the thickness of the ND filter as well as the the variation in the AR coating. The tolerance in the thickness is ±0.2 mm and the variation n the AR coating is less than 1% and is detailed in this link - ttps://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=5840&tabname=AR%20coating

Hailong He (posted 2020-05-07 10:22:37.33)

Hi, I am interested in the ND filter at wavelenght of 532 nm. I would like to ask the damage threshold of them. I am using a pulse laser (2 ns) with maximum peak power of 200KW. Is this power in the safe range of the density filters? Thanks, Hailong

YLohia (posted 2020-05-08 08:39:05.0)

Hello Hailong, thank you for contacting Thorlabs. These filters are designed for < 1 W CW applications. Unfortunately, we do not expect these filters to perform well for your 2 ns, 1 kHz, 200 kW peak power pulses at 532 nm. Instead, we recommend looking into our uncoated absorptive ND filters on this page : https://www.thorlabs.us/newgrouppage9.cfm?objectgroup_id=266.

Ali Ojaghloo (posted 2020-04-28 00:39:38.007)

dear services, I have some of your company product such as ND filter, Photodiode, lenses and etc. unfortunately in user manual and your website information about these damage threshold not anything. please give me some inform about it to calculate max power that we can use? I have NEIR 40A-c, NE 40A-A, i have about ten models of photodiode of your products such DET10A/M which you don't mentioned about

asundararaj (posted 2020-05-04 05:08:57.0)

Thank you for contacting Thorlabs. While we do not have an official spec for the damage threshold for the NE40A-A and the NEIR40A-C, I have contacted you directly to see if these would suit your application. As for the DET10A/M, while we typically do not spec a damage threshold for our detectors, the power is limited by the max reverse current on the photodiode - 5 mA. The Max optical power can be found from the responsivity at your wavelength using the following equation, Maximum Optical Power (in W) = Maximum PhotoCurrent (in A) * Responsivity (in A/W)

user (posted 2020-04-26 21:05:31.333)

Is there an LIDT for the ND filters?

YLohia (posted 2020-04-27 10:50:16.0)

Thank you for contacting Thorlabs. These filters are designed for applications with < 1 W power. I have reached out to you directly to offer suggestions based on your specific requirements.

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 #	OD^b	Thickness^c
NE01A-A	0.1 ± 0.005	0.6 mm
NE02A-A	0.2 ± 0.01	1.4 mm
NE03A-A	0.3 ± 0.015	2.3 mm
NE04A-A	0.4 ± 0.02	0.7 mm
NE05A-A	0.5 ± 0.025	0.9 mm
NE06A-A	0.6 ± 0.03	1.1 mm
NE07A-A	0.7 ± 0.04	1.3 mm
NE08A-A	0.8 ± 0.05	1.5 mm
NE09A-A	0.9 ± 0.05	1.7 mm

Click the blue icon to view a plot of the transmission.
Measured at 633 nm before the AR coating was applied.
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 #	OD^b	Thickness^c
NE10A-A	1.0 ± 0.05	1.9 mm
NE13A-A	1.3 ± 0.065	2.5 mm
NE15A-A	1.5 ± 0.08	2.9 mm
NE20A-A	2.0 ± 0.1	1.4 mm
NE30A-A	3.0 ± 0.15	2.1 mm
NE40A-A	4.0 ± 0.2	2.8 mm
NE50A-A	5.0 ± 0.25	3.6 mm
NE60A-A	6.0 ± 0.3	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 Ø25 mm Absorptive Neutral Density Filter, SM1-Threaded Mount, ARC: 350-700 nm, OD: 0.1

$76.83

5-8 Days

NE02A-A Ø25 mm Absorptive Neutral Density Filter, SM1-Threaded Mount, ARC: 350-700 nm, OD: 0.2

$76.83

Today

NE03A-A Ø25 mm Absorptive Neutral Density Filter, SM1-Threaded Mount, ARC: 350-700 nm, OD: 0.3

$79.27

Today

NE04A-A Ø25 mm Absorptive Neutral Density Filter, SM1-Threaded Mount, ARC: 350-700 nm, OD: 0.4

$76.83

Today

NE05A-A Ø25 mm Absorptive Neutral Density Filter, SM1-Threaded Mount, ARC: 350-700 nm, OD: 0.5

$76.83

Today

NE06A-A Ø25 mm Absorptive Neutral Density Filter, SM1-Threaded Mount, ARC: 350-700 nm, OD: 0.6

$76.83

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NE07A-A NEW!Ø25 mm Absorptive Neutral Density Filter, SM1-Threaded Mount, ARC: 350-700 nm, OD: 0.7

$76.83

Today

NE08A-A NEW!Ø25 mm Absorptive Neutral Density Filter, SM1-Threaded Mount, ARC: 350-700 nm, OD: 0.8

$76.83

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NE09A-A NEW!Ø25 mm Absorptive Neutral Density Filter, SM1-Threaded Mount, ARC: 350-700 nm, OD: 0.9

$76.83

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NE10A-A Ø25 mm Absorptive Neutral Density Filter, SM1-Threaded Mount, ARC: 350-700 nm, OD: 1.0

$79.27

Today

NE13A-A Ø25 mm Absorptive Neutral Density Filter, SM1-Threaded Mount, ARC: 350-700 nm, OD: 1.3

$76.83

Today

NE15A-A NEW!Ø25 mm Absorptive Neutral Density Filter, SM1-Threaded Mount, ARC: 350-700 nm, OD: 1.5

$76.83

Today

NE20A-A Ø25 mm Absorptive Neutral Density Filter, SM1-Threaded Mount, ARC: 350-700 nm, OD: 2.0

$79.27

Today

NE30A-A Ø25 mm Absorptive Neutral Density Filter, SM1-Threaded Mount, ARC: 350-700 nm, OD: 3.0

$76.83

Today

NE40A-A Ø25 mm Absorptive Neutral Density Filter, SM1-Threaded Mount, ARC: 350-700 nm, OD: 4.0

$76.83

Today

NE50A-A Ø25 mm Absorptive Neutral Density Filter, SM1-Threaded Mount, ARC: 350-700 nm, OD: 5.0

$76.83

Today

NE60A-A Ø25 mm Absorptive Neutral Density Filter, SM1-Threaded Mount, ARC: 350-700 nm, OD: 6.0

$76.83

Today

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

Features

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