Infrared 700-6000nm Neutral Density Filters
Definition:
A neutral density filter (ND Filter) reduces or modifies the amount of light transmitted through an optical system across a specified range. Often the result is a near flat transmission across a range, a basic example would be sunglasses, to reduce transmission and prevent the eyes being over exposed. Neutral density filters are also be used to balance optical systems. In another example they can be used to reduce the radiation incident on a detector by a measured amount. In such applications such the detector can be calibrated and used as a power meter for it’s sensitivity range.
Design and Manufacture:
We design and manufacture Neutral Density Filters across the infrared range between 700 nanometres to 6000 nanometres to any custom specification. Please refer to our visible neutral density filter page for neutral density filters from 400 – 700nm.
Supplying Optics:
We hold an extensive inventory of stock wafer substrates, including Glass, Sapphire, Silicon, Germanium, Fused Silica, Calcium Fluoride, and more, available in various thicknesses and ready for immediate coating. Post-coating, these substrates can be swiftly diced, or core drilled, we can supply ND filters at significantly reduced lead times, often less than two weeks. Additionally, we have a network of trusted optics suppliers, whom we regularly audit, to provide custom optics. This allows us to offer a complete comprehensive solution, simplifying your procurement process.
Coat Only Service:
We also provide an express coating service for customer-supplied optics, with lead times as short as 1 week. If you already have the optics, we are more than happy to coat them for you. With hundreds of different-sized tooling jigs accumulated over years of manufacturing, we can often save on both tooling costs and lead times by utilising existing tooling or by making minor in-house modifications to suit your requirements.
Please contact us to discuss your specific requirements.


Case Studies

Mid IR ND Filter 52%, 32%, 10%, 1%

Infrared ND Filter 60% T
Applications

Military and Defence:
Neutral density filters are important in military and defence applications, one example being in target designation where ND filters are used to manage the intensity of lasers, ensuring that they illuminate the target without revealing the operator’s position or causing unintended damage. ND filters are also used in range finding, helping to regulate the intensity of the laser pulse, providing accurate distance measurements while protecting sensitive optical components from high-intensity reflections.

Laser Systems and Optics:
ND filters are used to reduce the intensity of laser beams in research labs, allowing for safe examination and manipulation of the beams without damaging sensitive equipment. In industrial applications, such as material processing or medical devices, ND filters help in calibrating laser systems by providing consistent attenuation.
In industrial laser cutting and welding, ND filters are used to manage the intensity of IR lasers, ensuring precision and preventing damage to materials and equipment. ND filters are also employed in safety goggles and protective barriers to attenuate high-intensity IR laser beams, protecting workers from potential eye and skin damage.

Microscopy:
ND filters are used to control the intensity of light sources to prevent photobleaching and photodamage to samples. This is particularly important in biological research where delicate specimens are studied.

Spectroscopy:
ND filters help in controlling the intensity of IR light sources in spectroscopic analysis, enabling accurate measurement of material properties and chemical compositions. They are also used in Fourier Transform Infrared (FTIR) Spectroscopy to balance the intensity of IR light in FTIR spectroscopy, improving the signal-to-noise ratio and the quality of spectral data.

Optical Communication:
In fibre optic communication systems, ND filters are used to manage the power levels of IR signals, ensuring optimal transmission and preventing damage to sensitive components.

Detector Protection:
Neutral Density Filters are used to protect sensitive detectors from being saturated or damaged by high-intensity light sources.

Remote Sensing and Environmental Monitoring:
ND filters are used in satellite sensors to control the intensity of IR light reflected from the Earth’s surface, enhancing image quality and providing valuable data for environmental monitoring and land use analysis. In unmanned aerial vehicles (UAVs) and drones, ND filters help in capturing clear IR images for applications such as agricultural monitoring, forest management, and disaster assessment.

Industrial Inspection and Quality Control:
ND filters are used in IR-based Non-Destructive Testing methods to control the illumination and improve the detection of defects in materials and structures. In industrial automation, ND filters enhance the performance of IR machine vision systems by regulating light intensity and improving image contrast for accurate inspection and sorting.

Optical Instrumentation:
In the calibration of optical sensors and cameras, ND filters are used to simulate different lighting conditions and ensure accurate sensor responses. ND filters are also part of quality control processes in the manufacturing of optical components, ensuring that products meet specified performance criteria under various lighting conditions.

Automotive Industry:
ND filters are used in IR sensors for advanced driver assistance systems (ADAS) to manage the intensity of IR light, ensuring reliable performance of features like night vision and collision avoidance, this means that they will play a key role in the advancements of driverless car technology.

Security and Surveillance:
ND filters are used in IR night vision devices to control the intensity of infrared illumination, providing clear and detailed images in low-light or no-light conditions. Surveillance Cameras use ND filters help in optimising the performance of IR surveillance cameras, ensuring consistent image quality regardless of lighting changes.

Infrared Thermal Imaging:
ND filters are used to control the infrared light reaching thermal imaging sensors, ensuring accurate temperature readings and high-quality thermal images. This is vital in industrial inspection, building diagnostics, and firefighting.

Medical Thermography:
In medical diagnostics, ND filters help in capturing clear thermal images of the human body, aiding the detection of conditions such as inflammation and poor blood circulation.

Scientific Research:
In astronomical observations, ND filters are used to attenuate the light from bright IR sources like stars and planets, allowing scientists to study faint objects and phenomena. ND filters also assist in controlling IR light in experiments involving live tissues and organisms, protecting samples from excessive exposure and enhancing observation accuracy.