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Wedged N-BK7 Reflective Neutral Density Filters


  • Optical Densities from 0.1 to 4.0
  • 30 arcmin Wedge
  • Attenuation for the 350 - 1100 nm Range

NDW01B

Ø25 mm
Optical Density of 0.1

NDW40B

Ø25 mm
Optical Density of 4.0

NDW02B ND Filter
in an LMR1 Lens Mount

30 arcmin Wedge

1.0 mm
(0.04")

Related Items


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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 - 1650 nm)
Mounted Neutral Density Filter Kits
Unmounted
Distorted Wavefront
Click to Enlarge

NDW03B Wedged ND Filter in an RSP1 Rotation Mount
Optic Cleaning Tutorial

Features

  • Ø25 mm (Ø0.98") Reflective Neutral Density Filters
  • 30 arcmin Wedge for Reducing Cavity Feedback and Interference
  • Attenuates Over the 350 to 1100 nm Wavelength Range
  • Optical Densities Ranging from 0.1 to 4.0
  • Edge Blackening Available Upon Request

Thorlabs' Wedged Reflective (or Metallic) Neutral Density (ND) Filters provide uniform attenuation over the broad spectral range from 350 - 1100 nm, with optical densities ranging from 0.1 to 4.0. A 30 arcmin wedge on one side of the filter, as shown in the drawing above, helps to eliminate fringe patterns and reduce cavity feedback. This wedge design will also improve the performance of the filters when used in a stacked configuration. Refer to the Specs tab above for detailed information about the average transmission obtained with each of our reflective neutral density filters. The Graphs tab contains plots of the transmission and reflection for each filter for a broad wavelength range.

These filters consist of a N-BK7 glass substrate with a metal (Inconel) coating deposited on the wedged surface. Inconel is a metallic alloy that ensures flat spectral response from the UV to the near IR. Unprotected metal coatings like this should only be cleaned by blown air, never touched, as contact may cause scratching to the unprotected surface. Although these are reflective ND filters, the Inconel coating does absorb some of the incident light, which limits the use of these filters to low-power applications. Inconel is resistant to aging under normal conditions; however, it will oxidize at elevated temperatures. To prevent oxidation, Thorlabs recommends using these ND filters at temperatures below 100 °C. To achieve the best performance light should be incident on the side with the Inconel coating.

Thorlabs also offers UV fused silica and variable reflective ND filters, as well as a complete line of absorptive ND filters in several sizes; the table above contains links to all of the available options.

Please note that Thorlabs Neutral Density filters are not designed as laser safety equipment. For lab safety, Thorlabs offers an extensive line of safety and blackout products, such as beam blocks, that significantly reduce exposure to the stray or reflected light.

Item # Optical Densitya
(Transmission)
Transmission Datab
(Raw Data)
NDW01B 0.1 (79%) WedgedND Filter
NDW02B 0.2 (63%) WedgedND Filter
NDW03B 0.3 (50%) WedgedND Filter
NDW04B 0.4 (40%) WedgedND Filter
NDW05B 0.5 (32%) WedgedND Filter
NDW06B 0.6 (25%) WedgedND Filter
NDW10B 1.0 (10%) WedgedND Filter
NDW13B 1.3 (5%) WedgedND Filter
NDW20B 2.0 (1%) WedgedND Filter
NDW30B 3.0 (0.1%) WedgedND Filter
NDW40B 4.0 (0.01%) WedgedND Filter
  • At a Wavelength of 633 nm
  • The black dashed line indicates the designated optical density.
Common Specifications
Substrate N-BK7a Glass
Wedge 30 ±10 arcmin
Diameter 25.0 +0.0/-0.2 mm
Thickness 1.0 ± 0.25 mm
Clear Aperture >90% Outer Diameter
Surface Flatness (Over Ø25 mm Area) <5λ
Surface Quality 40-20 Scratch-Dig
  • Click Link for Detailed Specifications on the Substrate Glass
Item # Damage Thresholds
NDW03B CWa 16 W/cm (532 nm, CW, Ø0.051 mm)
Pulsed 0.025 J/cm2 (532 nm, 10 ns, 10 Hz, Ø0.493 mm)
NDW10B CWa 5 W/cm (532 nm, CW, Ø0.019 mm)
Pulsed 0.025 J/cm2 (532 nm, 10 ns, 10 Hz, Ø0.566 mm)
NDW20B CWa 25 W/cm (532 nm, CW, Ø0.049 mm)
Pulsed 0.025 J/cm2 (532 nm, 10 ns, 10 Hz, Ø0.493 mm)
  • The power density of your beam should be calculated in terms of W/cm. For an explanation of why the linear power density provides the best metric for long pulse and CW sources, please see the Damage Thresholds tab.

Optical Density

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 reflection of the incident light. For higher transmission and less reflection, 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 (%).

An Excel file with raw transmission and reflectance data for all N-BK7 Reflective ND filters is also available.

 TransmissionReflectance
OD 0.1-0.6Transmission OD 0.1 - 0.6
Click to Enlarge
Reflectivity OD 1.0 - 2.0
Click to Enlarge
OD 1.0-2.0Transmission OD 0.1 - 0.6
Click to Enlarge
Visible transmission OD 1.0 - 2.0
Click to Enlarge
OD 3.0-4.0Transmission OD 3.0 - 4.0
Click to Enlarge

Click for Transmission in the 400-700 nm Wavelength Range
Reflectivity OD 3.0 - 4.0
Click to Enlarge
Engraved Back of OAP
Click to Enlarge

Water Spectrum as Recorded Through a Standard and Wedged ND filter

Comparison of Standard and Wedged ND Filters
We present laboratory measurements on the difference in the etalon effect between our standard reflective neutral density (ND) filters and our wedged reflective ND filters. In many broadband scattering or absorption measurements, it is important to understand how intensity fluctuations through the utilized optics can impact the measurement. While it is known that parallel surfaces introduce significant wavelength-dependent intensity fluctuations, we find that utilizing a wedged geometry significantly reduces these etalon effects.

For our experiment we used the SLS202 Stabilized Light Source as the broadband, fiber-coupled light source. The F260FC-C Fiber Collimator, held in the KAD11F Kinematic Pitch/Yaw Adapter, collimates the light out of the fiber. The collimated light is incident upon the ND filter that is being investigated before entering the OSA203B Optical Spectrum Analyzer. The OSA has a spectral resolution of 7.5 GHz (0.25 cm-1) and the traces were averaged (>100 scans) in order to reduce noise and allow for more accurate analysis. The data focused on a wavelength range of 1820 - 1845 nm, which covers the NIR water spectrum. Since the absorption spectrum of water is well known, it is ideal to use as a comparison to evaluate the performance difference between these two styles of ND filter.

Lab Facts Complete Summary

The figure to the right summarizes the measured results for etalon effects through reflective neutral density filters. The etalon effects are quite stark, and we can see in the case of the standard ND filters that details of the water spectrum are lost to the intensity fluctuations of the background levels. By contrast, the wedged ND filters have a relatively clean signal with well-defined peaks. Data is presented for unmounted standard and wedged ND filters, though the results hold for mounted filters as well. Data is also compared to the HITRAN water spectrum standard. For details on the experimental setup employed and the results summarized here, please click here.

Damage Threshold Specifications
Optical Density Damage Thresholds
0.3 CWa 16 W/cm (532 nm, CW, Ø0.051 mm)
Pulsed 0.025 J/cm2 (532 nm, 10 ns, 10 Hz, Ø0.493 mm)
1.0 CWa 5 W/cm (532 nm, CW, Ø0.019 mm)
Pulsed 0.025 J/cm2 (532 nm, 10 ns, 10 Hz, Ø0.566 mm)
2.0 CWa 25 W/cm (532 nm, CW, Ø0.049 mm)
Pulsed 0.025 J/cm2 (532 nm, 10 ns, 10 Hz, Ø0.493 mm)
  • The power density of your beam should be calculated in terms of W/cm. For an explanation of why the linear power density provides the best metric for long pulse and CW sources, please see the "Continuous Wave and Long-Pulse Lasers" section below.

Damage Threshold Data for Thorlabs' Reflective ND Filters

The specifications to the right are measured data for Thorlabs' reflective neutral density filters. Damage threshold specifications are constant for a given optical density coating, regardless of the size of the filter.

 

Laser Induced Damage Threshold Tutorial

The following is a general overview of how laser induced damage thresholds are measured and how the values may be utilized in determining the appropriateness of an optic for a given application. When choosing optics, it is important to understand the Laser Induced Damage Threshold (LIDT) of the optics being used. The LIDT for an optic greatly depends on the type of laser you are using. Continuous wave (CW) lasers typically cause damage from thermal effects (absorption either in the coating or in the substrate). Pulsed lasers, on the other hand, often strip electrons from the lattice structure of an optic before causing thermal damage. Note that the guideline presented here assumes room temperature operation and optics in new condition (i.e., within scratch-dig spec, surface free of contamination, etc.). Because dust or other particles on the surface of an optic can cause damage at lower thresholds, we recommend keeping surfaces clean and free of debris. For more information on cleaning optics, please see our Optics Cleaning tutorial.

Testing Method

Thorlabs' LIDT testing is done in compliance with ISO/DIS 11254 and ISO 21254 specifications.

First, a low-power/energy beam is directed to the optic under test. The optic is exposed in 10 locations to this laser beam for 30 seconds (CW) or for a number of pulses (pulse repetition frequency specified). After exposure, the optic is examined by a microscope (~100X magnification) for any visible damage. The number of locations that are damaged at a particular power/energy level is recorded. Next, the power/energy is either increased or decreased and the optic is exposed at 10 new locations. This process is repeated until damage is observed. The damage threshold is then assigned to be the highest power/energy that the optic can withstand without causing damage. A histogram such as that below represents the testing of one BB1-E02 mirror.

LIDT metallic mirror
The photograph above is a protected aluminum-coated mirror after LIDT testing. In this particular test, it handled 0.43 J/cm2 (1064 nm, 10 ns pulse, 10 Hz, Ø1.000 mm) before damage.
LIDT BB1-E02
Example Test Data
Fluence # of Tested Locations Locations with Damage Locations Without Damage
1.50 J/cm2 10 0 10
1.75 J/cm2 10 0 10
2.00 J/cm2 10 0 10
2.25 J/cm2 10 1 9
3.00 J/cm2 10 1 9
5.00 J/cm2 10 9 1

According to the test, the damage threshold of the mirror was 2.00 J/cm2 (532 nm, 10 ns pulse, 10 Hz, Ø0.803 mm). Please keep in mind that these tests are performed on clean optics, as dirt and contamination can significantly lower the damage threshold of a component. While the test results are only representative of one coating run, Thorlabs specifies damage threshold values that account for coating variances.

Continuous Wave and Long-Pulse Lasers

When an optic is damaged by a continuous wave (CW) laser, it is usually due to the melting of the surface as a result of absorbing the laser's energy or damage to the optical coating (antireflection) [1]. Pulsed lasers with pulse lengths longer than 1 µs can be treated as CW lasers for LIDT discussions.

When pulse lengths are between 1 ns and 1 µs, laser-induced damage can occur either because of absorption or a dielectric breakdown (therefore, a user must check both CW and pulsed LIDT). Absorption is either due to an intrinsic property of the optic or due to surface irregularities; thus LIDT values are only valid for optics meeting or exceeding the surface quality specifications given by a manufacturer. While many optics can handle high power CW lasers, cemented (e.g., achromatic doublets) or highly absorptive (e.g., ND filters) optics tend to have lower CW damage thresholds. These lower thresholds are due to absorption or scattering in the cement or metal coating.

Linear Power Density Scaling

LIDT in linear power density vs. pulse length and spot size. For long pulses to CW, linear power density becomes a constant with spot size. This graph was obtained from [1].

Intensity Distribution

Pulsed lasers with high pulse repetition frequencies (PRF) may behave similarly to CW beams. Unfortunately, this is highly dependent on factors such as absorption and thermal diffusivity, so there is no reliable method for determining when a high PRF laser will damage an optic due to thermal effects. For beams with a high PRF both the average and peak powers must be compared to the equivalent CW power. Additionally, for highly transparent materials, there is little to no drop in the LIDT with increasing PRF.

In order to use the specified CW damage threshold of an optic, it is necessary to know the following:

  1. Wavelength of your laser
  2. Beam diameter of your beam (1/e2)
  3. Approximate intensity profile of your beam (e.g., Gaussian)
  4. Linear power density of your beam (total power divided by 1/e2 beam diameter)

Thorlabs expresses LIDT for CW lasers as a linear power density measured in W/cm. In this regime, the LIDT given as a linear power density can be applied to any beam diameter; one does not need to compute an adjusted LIDT to adjust for changes in spot size, as demonstrated by the graph to the right. Average linear power density can be calculated using the equation below. 

The calculation above assumes a uniform beam intensity profile. You must now consider hotspots in the beam or other non-uniform intensity profiles and roughly calculate a maximum power density. For reference, a Gaussian beam typically has a maximum power density that is twice that of the uniform beam (see lower right).

Now compare the maximum power density to that which is specified as the LIDT for the optic. If the optic was tested at a wavelength other than your operating wavelength, the damage threshold must be scaled appropriately. A good rule of thumb is that the damage threshold has a linear relationship with wavelength such that as you move to shorter wavelengths, the damage threshold decreases (i.e., a LIDT of 10 W/cm at 1310 nm scales to 5 W/cm at 655 nm):

CW Wavelength Scaling

While this rule of thumb provides a general trend, it is not a quantitative analysis of LIDT vs wavelength. In CW applications, for instance, damage scales more strongly with absorption in the coating and substrate, which does not necessarily scale well with wavelength. While the above procedure provides a good rule of thumb for LIDT values, please contact Tech Support if your wavelength is different from the specified LIDT wavelength. If your power density is less than the adjusted LIDT of the optic, then the optic should work for your application. 

Please note that we have a buffer built in between the specified damage thresholds online and the tests which we have done, which accommodates variation between batches. Upon request, we can provide individual test information and a testing certificate. The damage analysis will be carried out on a similar optic (customer's optic will not be damaged). Testing may result in additional costs or lead times. Contact Tech Support for more information.

Pulsed Lasers

As previously stated, pulsed lasers typically induce a different type of damage to the optic than CW lasers. Pulsed lasers often do not heat the optic enough to damage it; instead, pulsed lasers produce strong electric fields capable of inducing dielectric breakdown in the material. Unfortunately, it can be very difficult to compare the LIDT specification of an optic to your laser. There are multiple regimes in which a pulsed laser can damage an optic and this is based on the laser's pulse length. The highlighted columns in the table below outline the relevant pulse lengths for our specified LIDT values.

Pulses shorter than 10-9 s cannot be compared to our specified LIDT values with much reliability. In this ultra-short-pulse regime various mechanics, such as multiphoton-avalanche ionization, take over as the predominate damage mechanism [2]. In contrast, pulses between 10-7 s and 10-4 s may cause damage to an optic either because of dielectric breakdown or thermal effects. This means that both CW and pulsed damage thresholds must be compared to the laser beam to determine whether the optic is suitable for your application.

Pulse Duration t < 10-9 s 10-9 < t < 10-7 s 10-7 < t < 10-4 s t > 10-4 s
Damage Mechanism Avalanche Ionization Dielectric Breakdown Dielectric Breakdown or Thermal Thermal
Relevant Damage Specification No Comparison (See Above) Pulsed Pulsed and CW CW

When comparing an LIDT specified for a pulsed laser to your laser, it is essential to know the following:

Energy Density Scaling

LIDT in energy density vs. pulse length and spot size. For short pulses, energy density becomes a constant with spot size. This graph was obtained from [1].

  1. Wavelength of your laser
  2. Energy density of your beam (total energy divided by 1/e2 area)
  3. Pulse length of your laser
  4. Pulse repetition frequency (prf) of your laser
  5. Beam diameter of your laser (1/e2 )
  6. Approximate intensity profile of your beam (e.g., Gaussian)

The energy density of your beam should be calculated in terms of J/cm2. The graph to the right shows why expressing the LIDT as an energy density provides the best metric for short pulse sources. In this regime, the LIDT given as an energy density can be applied to any beam diameter; one does not need to compute an adjusted LIDT to adjust for changes in spot size. This calculation assumes a uniform beam intensity profile. You must now adjust this energy density to account for hotspots or other nonuniform intensity profiles and roughly calculate a maximum energy density. For reference a Gaussian beam typically has a maximum energy density that is twice that of the 1/e2 beam.

Now compare the maximum energy density to that which is specified as the LIDT for the optic. If the optic was tested at a wavelength other than your operating wavelength, the damage threshold must be scaled appropriately [3]. A good rule of thumb is that the damage threshold has an inverse square root relationship with wavelength such that as you move to shorter wavelengths, the damage threshold decreases (i.e., a LIDT of 1 J/cm2 at 1064 nm scales to 0.7 J/cm2 at 532 nm):

Pulse Wavelength Scaling

You now have a wavelength-adjusted energy density, which you will use in the following step.

Beam diameter is also important to know when comparing damage thresholds. While the LIDT, when expressed in units of J/cm², scales independently of spot size; large beam sizes are more likely to illuminate a larger number of defects which can lead to greater variances in the LIDT [4]. For data presented here, a <1 mm beam size was used to measure the LIDT. For beams sizes greater than 5 mm, the LIDT (J/cm2) will not scale independently of beam diameter due to the larger size beam exposing more defects.

The pulse length must now be compensated for. The longer the pulse duration, the more energy the optic can handle. For pulse widths between 1 - 100 ns, an approximation is as follows:

Pulse Length Scaling

Use this formula to calculate the Adjusted LIDT for an optic based on your pulse length. If your maximum energy density is less than this adjusted LIDT maximum energy density, then the optic should be suitable for your application. Keep in mind that this calculation is only used for pulses between 10-9 s and 10-7 s. For pulses between 10-7 s and 10-4 s, the CW LIDT must also be checked before deeming the optic appropriate for your application.

Please note that we have a buffer built in between the specified damage thresholds online and the tests which we have done, which accommodates variation between batches. Upon request, we can provide individual test information and a testing certificate. Contact Tech Support for more information.


[1] R. M. Wood, Optics and Laser Tech. 29, 517 (1998).
[2] Roger M. Wood, Laser-Induced Damage of Optical Materials (Institute of Physics Publishing, Philadelphia, PA, 2003).
[3] C. W. Carr et al., Phys. Rev. Lett. 91, 127402 (2003).
[4] N. Bloembergen, Appl. Opt. 12, 661 (1973).

In order to illustrate the process of determining whether a given laser system will damage an optic, a number of example calculations of laser induced damage threshold are given below. For assistance with performing similar calculations, we provide a spreadsheet calculator that can be downloaded by clicking the button to the right. To use the calculator, enter the specified LIDT value of the optic under consideration and the relevant parameters of your laser system in the green boxes. The spreadsheet will then calculate a linear power density for CW and pulsed systems, as well as an energy density value for pulsed systems. These values are used to calculate adjusted, scaled LIDT values for the optics based on accepted scaling laws. This calculator assumes a Gaussian beam profile, so a correction factor must be introduced for other beam shapes (uniform, etc.). The LIDT scaling laws are determined from empirical relationships; their accuracy is not guaranteed. Remember that absorption by optics or coatings can significantly reduce LIDT in some spectral regions. These LIDT values are not valid for ultrashort pulses less than one nanosecond in duration.

Intensity Distribution
A Gaussian beam profile has about twice the maximum intensity of a uniform beam profile.

CW Laser Example
Suppose that a CW laser system at 1319 nm produces a 0.5 W Gaussian beam that has a 1/e2 diameter of 10 mm. A naive calculation of the average linear power density of this beam would yield a value of 0.5 W/cm, given by the total power divided by the beam diameter:

CW Wavelength Scaling

However, the maximum power density of a Gaussian beam is about twice the maximum power density of a uniform beam, as shown in the graph to the right. Therefore, a more accurate determination of the maximum linear power density of the system is 1 W/cm.

An AC127-030-C achromatic doublet lens has a specified CW LIDT of 350 W/cm, as tested at 1550 nm. CW damage threshold values typically scale directly with the wavelength of the laser source, so this yields an adjusted LIDT value:

CW Wavelength Scaling

The adjusted LIDT value of 350 W/cm x (1319 nm / 1550 nm) = 298 W/cm is significantly higher than the calculated maximum linear power density of the laser system, so it would be safe to use this doublet lens for this application.

Pulsed Nanosecond Laser Example: Scaling for Different Pulse Durations
Suppose that a pulsed Nd:YAG laser system is frequency tripled to produce a 10 Hz output, consisting of 2 ns output pulses at 355 nm, each with 1 J of energy, in a Gaussian beam with a 1.9 cm beam diameter (1/e2). The average energy density of each pulse is found by dividing the pulse energy by the beam area:

Pulse Energy Density

As described above, the maximum energy density of a Gaussian beam is about twice the average energy density. So, the maximum energy density of this beam is ~0.7 J/cm2.

The energy density of the beam can be compared to the LIDT values of 1 J/cm2 and 3.5 J/cm2 for a BB1-E01 broadband dielectric mirror and an NB1-K08 Nd:YAG laser line mirror, respectively. Both of these LIDT values, while measured at 355 nm, were determined with a 10 ns pulsed laser at 10 Hz. Therefore, an adjustment must be applied for the shorter pulse duration of the system under consideration. As described on the previous tab, LIDT values in the nanosecond pulse regime scale with the square root of the laser pulse duration:

Pulse Length Scaling

This adjustment factor results in LIDT values of 0.45 J/cm2 for the BB1-E01 broadband mirror and 1.6 J/cm2 for the Nd:YAG laser line mirror, which are to be compared with the 0.7 J/cm2 maximum energy density of the beam. While the broadband mirror would likely be damaged by the laser, the more specialized laser line mirror is appropriate for use with this system.

Pulsed Nanosecond Laser Example: Scaling for Different Wavelengths
Suppose that a pulsed laser system emits 10 ns pulses at 2.5 Hz, each with 100 mJ of energy at 1064 nm in a 16 mm diameter beam (1/e2) that must be attenuated with a neutral density filter. For a Gaussian output, these specifications result in a maximum energy density of 0.1 J/cm2. The damage threshold of an NDUV10A Ø25 mm, OD 1.0, reflective neutral density filter is 0.05 J/cm2 for 10 ns pulses at 355 nm, while the damage threshold of the similar NE10A absorptive filter is 10 J/cm2 for 10 ns pulses at 532 nm. As described on the previous tab, the LIDT value of an optic scales with the square root of the wavelength in the nanosecond pulse regime:

Pulse Wavelength Scaling

This scaling gives adjusted LIDT values of 0.08 J/cm2 for the reflective filter and 14 J/cm2 for the absorptive filter. In this case, the absorptive filter is the best choice in order to avoid optical damage.

Pulsed Microsecond Laser Example
Consider a laser system that produces 1 µs pulses, each containing 150 µJ of energy at a repetition rate of 50 kHz, resulting in a relatively high duty cycle of 5%. This system falls somewhere between the regimes of CW and pulsed laser induced damage, and could potentially damage an optic by mechanisms associated with either regime. As a result, both CW and pulsed LIDT values must be compared to the properties of the laser system to ensure safe operation.

If this relatively long-pulse laser emits a Gaussian 12.7 mm diameter beam (1/e2) at 980 nm, then the resulting output has a linear power density of 5.9 W/cm and an energy density of 1.2 x 10-4 J/cm2 per pulse. This can be compared to the LIDT values for a WPQ10E-980 polymer zero-order quarter-wave plate, which are 5 W/cm for CW radiation at 810 nm and 5 J/cm2 for a 10 ns pulse at 810 nm. As before, the CW LIDT of the optic scales linearly with the laser wavelength, resulting in an adjusted CW value of 6 W/cm at 980 nm. On the other hand, the pulsed LIDT scales with the square root of the laser wavelength and the square root of the pulse duration, resulting in an adjusted value of 55 J/cm2 for a 1 µs pulse at 980 nm. The pulsed LIDT of the optic is significantly greater than the energy density of the laser pulse, so individual pulses will not damage the wave plate. However, the large average linear power density of the laser system may cause thermal damage to the optic, much like a high-power CW beam.


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Ø1" Wedged Reflective ND Filters

Item #Optical Densitya
(Transmission)
Transmission and
Reflectance Data
NDW01B0.1 (79%)info
NDW02B0.2 (63%)info
NDW03B0.3 (50%)info
NDW04B0.4 (40%)info
NDW05B0.5 (32%)info
NDW06B0.6 (25%)info
  • At a Wavelength of 633 nm
Item #Optical Densitya
(Transmission)
Transmission and
Reflectance Data
NDW10B1.0 (10%)info
NDW13B1.3 (5%)info
NDW20B2.0 (1%)info
NDW30B3.0 (0.1%)info
NDW40B4.0 (0.01%)info

Click on More Info Icon for a plot and downloadable data. The black dashed line indicates the designated optical density.

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NDW01B Support Documentation
NDW01BCustomer Inspired! Wedged Reflective Ø25 mm ND Filter, Optical Density: 0.1
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NDW10BCustomer Inspired! Wedged Reflective Ø25 mm ND Filter, Optical Density: 1.0
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NDW13BCustomer Inspired! Wedged Reflective Ø25 mm ND Filter, Optical Density: 1.3
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NDW20BCustomer Inspired! Wedged Reflective Ø25 mm ND Filter, Optical Density: 2.0
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NDW30BCustomer Inspired! Wedged Reflective Ø25 mm ND Filter, Optical Density: 3.0
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