Common Specifications
Transmission in Passbands	T_avg > 90%
Peak Optical Density in Blocking Region	>6.0
Clear Aperture	Ø21 mm
Surface Quality	60-40 (Scratch-Dig)
Transmitted Wavefront Error (@ 633 nm)	<λ/2
Angle of Incidence^a	0°
Coating	Dielectric Stack on Front Surface
Housing	Black-Anodized Lens Cell

Notch filters are designed for use at normal incidence but will function within the specifications stated above for an AOI of 0 ± 3°.

Features

Choose from 11 Center Wavelength Options
Ø1" and Ø25 mm Filters Avaliable
Peak Optical Density in Blocking Region: >6.0 (T < 0.0001%)
Dielectric Stack on Polished Glass Substrate
Compatible with Thorlabs' Filter Mounts and Filter Wheels

Notch filters, also commonly referred to as band-stop or band-rejection filters, are designed to transmit most wavelengths with little intensity loss while attenuating light within a specific wavelength range (the stop band) to a very low level. They are basically the inverse of bandpass filters, which offer high in-band transmission and high out-of-band rejection so as to only transmit light within a small wavelength range.

Notch filters are useful in applications where one needs to block light from a laser. For instance, to obtain good signal-to-noise ratios in Raman spectroscopy experiments, it is critical that light from the pump laser be blocked. This is achieved by placing a notch filter in the detection channel of the setup. In addition to spectroscopy, notch filters are commonly used in laser-based fluorescence instrumentation and biomedical laser systems.

As with all dielectric stack filters, the transmission is dependent on the angle of incidence. The central wavelength of the blocking region will shift to shorter wavelengths as the angle of incidence is increased. Please see the Transmission Graphs Tab for measured transmission data for each individual filter. Additionally, plots of the meausured Optical Density (OD) of these filters in the blocking region may be found on the OD Graphs tab.

Thorlabs' notch filters feature a dielectric coating on a polished glass substrate, which has excellent environmental durability. The dielectric stack provides high rejection through destructive interference and reflection in the stop band: the optical density is greater than 6.0 (corresponding to a transmission less than 0.0001%) within the stop band. We currently offer central stop-band wavelengths of 405, 488, 514, 533, 561, 594, 633, 658, 785, 808, or 1064 nm. Regardless of the filter chosen, the transmitted beam's wavefront error for light at normal incidence will be less than λ/2 at 633 nm. These filters also have an AR coating on the back surface to ensure >90% average transmission within the passing bands.

Each filter is housed in a black anodized aluminum ring that is labeled with an arrow indicating the design propagation direction. The ring mount makes handling easier as well as enhancing the blocking OD by limiting scattering. These filters can be mounted in our extensive line of filter mounts and wheels. We do not recommend removing the filter from its mount as the risk of damaging the filter is very high. However, custom unmounted filters are available; please contact Tech Support for more details.

Below are transmission plots for our notch filters, obtained at normal incidence. Although designed for use at normal incidence, the performance of these filters will not vary significantly if used within an AOI of ±3°, but the performance may differ slightly from that shown below. Please note that this measured data presented is typical, and performace may vary from lot to lot, especially outside of the specified wavelength range of each filter.

Our 633 nm filter (NF633-25) has a plot of the transmission as a function of the angle of incidence; this plot may be found by clicking the link below the transmission plot.

Plots of the Optical Density in the blocking region may be found on the OD Graphs tab above.

The plots below detail the optical density in the blocking region of our notch filters. Please note that this measured data presented is typical, and performace may vary from lot to lot, especially outside of the specified wavelength range of each filter.

For plots of % transmission vs. wavelength, please see the Transmission Graphs tab above.

Optical Density (OD) is related to transmission by the following relationship:

OD equation

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Posted Comments:

Poster: bdada

Posted Date: 2011-10-25 13:30:00.0

Response from Buki at Thorlabs: Thank you for your interest in Thorlabs products. We will contact you to discuss a discount and find out more about your specifications for the custom filter. Please contact TechSupport@thorlabs.com if you have further questions.

Poster: gustavo.demiguel

Posted Date: 2011-10-25 03:22:49.0

I am interested in purchasing the set of five notch filters but the price is quite high. would it be cheaper if I buy all together? Is there any possibility to design a filter with a narrower blocking peak, for example at 633 nm?

Poster: jjurado

Posted Date: 2011-08-17 18:13:00.0

Response from Javier at Thorlabs to charles.h.adams: We currently do not have concise damage threshold data for our notch filters, as the damage is highly dependent on whether the incident light is concentrated in the transmission or blocking region of the filter. Nevertheless, these filters should be able to withstand light intensities up to ~1W/cm^2.

Poster: charles.h.adams

Posted Date: 2011-08-17 11:12:03.0

What is the damage threshold for the NF1064-44 and NF533-17? Would these be appropriate for use with a nanosecond laser capable of, tens of mW/cm^2?

Poster: jjurado

Posted Date: 2011-04-04 11:53:00.0

Response from Javier at Thorlabs to Konstanze: Thank you very much for contacting us. The transmission of the NF1064-44 notch filter at 532 nm is close to 0%, so it is not suitable for your application. The FL532-10 filter would be a better match; however, at 2 W, you will most likely exceed the damage threshold of the filter, especially if the diameter of the beam is small. If possible, I would recommend attenuating the output from your laser. I will contact you directly for further support.

Poster: k.hild

Posted Date: 2011-04-04 11:19:20.0

I am interested in the notch filter to cut out the 1064 laser line. On the data sheet and in the specification it says that the transmission band starts at 800nm. I was assuming that the transmission is quite close to 100% for other wavelengths as well, but this is obviously not stated, so could you tell me what the transmission of the NF1064-44 Support Documentation NF1064-44 - Notch Filter, CWL = 1064 nm, FWHM = 44 nm filter is at 532nm (I want to use it to get most of the energy from at 532nm out of the laser but block the also produced 1064. I had also considered using a laser line filter: FL532-10 Support Documentation FL532-10 - Laser Line Filter, CWL=532 ± 2 nm, FWHM=10 ± 2 nm , but this one only lets 80% of the light through at the lasing line. As I am using a relative powerful laser (up to 2W)I am not sure I want that much heat dissapated in my filter. Regards, Konstanze

Poster: tor

Posted Date: 2010-11-19 16:28:53.0

Response from Tor at Thorlabs to kmcao: We may be able to provide custom dimensions. I will contact you directly for your specific requirements.

Poster: kmcao

Posted Date: 2010-11-19 15:26:17.0

the size can be larger as over 50mm?

Poster: Thorlabs

Posted Date: 2010-11-08 10:38:16.0

Response from Javier at Thorlabs to jcogger: in these notch filters, the rejected wavelength band is blocked through a combination of destructive interference and reflection, the level of which varies from filter to filter. I will contact you directly with pricing information and to follow up on your technical inquiry.

Poster: jcogger

Posted Date: 2010-11-08 09:40:34.0

Do these notch filters reflect or absorb the the blocked wavelength? What is quantity pricing? I would like to design these filters into my product but the piece price makes it prohibitive.

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