Rectangular Stepped ND Filters | SIMTRUM Photonics Store

Rectangular Stepped ND Filters can adjust the intensity of incoming light beam to be transmitted by translating across different segments along its length axis. The spectrum passes through will continue to maintain its neutral spectrum energy distribution. It can either be metallic-alloy variable density sheets or low-inversion variable density sheets. This filter is commonly used in laser and medical application. By combining two filters, fixed density attenuation effect across a greater area can be obtained. The spectral range of our filters features a wavelength of 250-2500nm.

BK7 is the most common optical glass used in high-quality optical components as it is a hard glass that can withstand a variety of physical and chemical exposure. Relatively scratch and chemical resistant, it has a low bubble and inclusion content, therefore making it an ideal choice for precision lenses. It is the ideal choice for general purpose visual and NIR applications as it has excellent transmission.

The level of attenuation is specified by Optical Density (OD) of the filter.

OD is defined as negative of the base 10 logarithm of the transmission coefficient,

The equation can be shown as:

OD= - Log10 (T/100)  ,Where T is transmission in percentage.

E.g. A Neutral Density Filter with T= 1% has OD of 2.

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