Reflective Neutral Density (ND) Filters
Reflective Neutral Density (ND) Filters have a uniform density value across their entire surface, allowing for a consistent level of light attenuation. The ratio of transmission to reflection changes according to the chosen density, which can be calculated using the equation: T(Percent Transmission)=.
Optical Density (OD) values in Reflective ND Filters are additive; for instance, stacking filters with OD values of 0.6 and 0.9 results in a combined density of 1.5.
These filters are widely used for attenuating light across a broad spectral range and are ideal for applications in lasers and photometers where excessive light power might cause damage or affect accuracy. For optimal performance, position the mirrored side of the filter toward the light source at a 0° angle of incidence.
Features:
- Spectrally Flat
- Maximum Accuracy and Neutrality at Moderate Price
- Use Stacks to Create Intermediate Density Values
Common specifications of reflective neutral density (ND) filters
Absorptive Neutral Density (ND) Filters
Our UV-NIR absorptive Neutral Density (ND) Filters offer consistent spectral transmittance from the ultraviolet to the near-infrared, attenuating light primarily through absorption with minimal reflection.
Their neutrality and density depend on both the material and thickness of the filter. For instance, our absorptive neutral density filters maintain a specific optical density, meaning that thickness is determined by the type of glass used.
These UV-NIR ND Filters feature excellent parallelism with superior surface characteristics to provide constant, ultra-broadband performance from 190 – 1700nm.
These ND filters are ideal for a range of applications including spectroscopy, machine vision, or ellipsometry, or for use with low power lasers.
These filters are ideal for light control applications, such as in measuring instruments and for exposure control in imaging. As optical density increases, some spectral variations may appear.
The optical density (OD) values in absorptive ND filters are additive, meaning that stacking a filter with an OD of 0.6 and another with an OD of 0.9 results in a combined density of 1.5.
The relationship between optical density and light transmission can be described by the equation: T=10^-ODx100(percent transmission).
Features:
- Constant Transmission from 190 – 1700nm
- Can be Stacked to Create Intermediate Density Values
- Multiple Optical Densities Available
Common specifications of UV-NIR neutral density (ND) filters from Notch Optics
UV-NIR ND Filters Spectrum Curves