The high-performance, multilayer broadband B coating deposited on each filter is designed to minimize surface reflections within the 650 - 1050 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 available 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.
Transmission and Optical Density of -B 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 Tolerancea
Substrate
Substrate Thicknessb
Ø1/2" Item #
Ø25 mm Item #
0.1
± 0.005
NG11
0.6 mm
NE501B-B
NE01B-B
0.2
± 0.01
NG11
1.4 mm
NE502B-B
NE02B-B
0.3
± 0.015
NG11
2.3 mm
NE503B-B
NE03B-B
0.4
± 0.02
NG4
0.7 mm
NE504B-B
NE04B-B
0.5
± 0.025
NG4
0.9 mm
NE505B-B
NE05B-B
0.6
± 0.03
NG4
1.1 mm
NE506B-B
NE06B-B
0.7
± 0.04
NG4
1.3 mm
NE507B-B
NE07B-B
0.8
± 0.05
NG4
1.5 mm
NE508B-B
NE08B-B
0.9
± 0.05
NG4
1.7 mm
NE509B-B
NE09B-B
1.0
± 0.05
NG4
1.9 mm
NE510B-B
NE10B-B
1.3
± 0.065
NG4
2.5 mm
NE513B-B
NE13B-B
1.5
± 0.08
NG4
2.9 mm
NE515B-B
NE15B-B
2.0
± 0.1
NG9
1.4 mm
NE520B-B
NE20B-B
3.0
± 0.15
NG9
2.1 mm
NE530B-B
NE30B-B
4.0
± 0.2
NG9
2.8 mm
NE540B-B
NE40B-B
5.0
± 0.25
NG9
3.6 mm
NE550B-B
NE50B-B
6.0
± 0.3
NG1
1.5 mm
NE560B-B
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
650 - 1050 nm
Reflectance (Average)
<0.5% per Surfacea
Surface Flatnessb
<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
Click to Enlarge Click Here for Raw Data The blue shaded region indicates the 650 - 1050 nm wavelength range over which the AR coating provides <0.5% average reflectance per surface.
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.
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.
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Additional Neutral Density Filters: Absorptive/Reflective