Circular Linear Variable Metallic Neutral Density Filters

A circular variable neutral density filter (ND filter) allows users to precisely attenuate or split the power of a transmitted beam by an arbitrary ratio. The density of this filter varies linearly with rotation angle, making it easy to attenuate or split a beam by a precise amount.

Filter OD varies linearly with rotation angle
Dual purposed as variable beamsplitter
OD achieved using fine broadband coating
Fused silica substrate for 250-2500 nm
2λ surface flatness and 80-50 scratch-dig

See All Features

Description	Compatibility	Price
100FS01DV.1 Circular Linear Variable Metallic ND FiltersNeutral Density Filter, Circular Linear Variable, UVFS, 100 mm, 0-1 OD	UNIVERSAL	$482
100FS02DV.2 Circular Linear Variable Metallic ND FiltersNeutral Density Filter, Circular Variable Metallic, UVFS, 100 mm, 0-2 OD	UNIVERSAL	$482
100FS04DV.4 Circular Linear Variable Metallic ND FiltersNeutral Density Filter, Circular Variable Metallic, UVFS, 100 mm, 0-4 OD	UNIVERSAL	$513
25FS01DV.1 Circular Linear Variable Metallic ND FiltersNeutral Density Filter, Circular Variable Metallic, UVFS, 25 mm, 0-1 OD	UNIVERSAL	$286
25FS02DV.2 Circular Linear Variable Metallic ND FiltersNeutral Density Filter, Circular Variable Metallic, UVFS, 25 mm, 0-2 OD	UNIVERSAL	$286
25FS04DV.4 Circular Linear Variable Metallic ND FiltersNeutral Density Filter, Circular Variable Metallic, UVFS, 25 mm, 0-4 OD	UNIVERSAL	$308
50FS01DV.1 Circular Linear Variable Metallic ND FiltersNeutral Density Filter, Circular Variable Metallic, UVFS, 50 mm, 0-1 OD	UNIVERSAL	$392
50FS02DV.2 Circular Linear Variable Metallic ND FiltersNeutral Density Filter, Circular Variable Metallic, UVFS, 50 mm, 0-2 OD	UNIVERSAL	$392
50FS04DV.4 Circular Linear Variable Metallic ND FiltersNeutral Density Filter, Circular Variable Metallic, UVFS, 50 mm, 0-4 OD	UNIVERSAL	$414

Features

Finely Control Beam Attenuation

These variable neutral density filters allow convenient adjustment of beam attenuation by simply rotating the filter. Optical density varies linearly with rotation angle across a 270° range from 0 up to the chosen maximum of OD1, OD2, or OD4. An arbitrary transmitted beam power may then be obtained easily using the angular markings to rotating the variable ND filter to the specific corresponding angle. Due to this linearity in density, the rotation may even be motorized to produce a precise logarithmic sweep in the transmitted beam power.

Wide Wavelength Range

Fused silica substrate for these ND filters allows the transparency from 250-2500 nm range.

Variable Beamsplitter Applications

These filters consist of a thin metallic coating of variable thickness. Because attenuation is primarily caused by reflection with only a small amount of absorption, these filters may optionally be used as variable beamsplitters.

Proper Orientation

To prevent unwanted interference from etalon effects, filters should be angled slightly with respect to the incident beam. To minimize back reflections, the filter should be oriented with the coated metallic surface facing the incident beam. Any light reflected from the uncoated second surface will pass through the metallic coating first, which will greatly attenuate unwanted back reflections.

Filter Mounting

We offer a variety of rotary mounts for the variable neutral density filter. Please check out the accessories section below for recommendations. Shown is model FR-CV-75 compact circular variable ND filter mount.

Accessories

Compatible Filter Rotators, (All Diameters)

	Compare	Description	Compatibility	Drawings, CAD & Specs	Avail.	Price
		FR-CV-75 ND Filter Rotator, Compact, 7.5 mm Hub, 8-32 and M4	UNIVERSAL			$73

Compatible Filter Rotators, (25-mm dia only)

Description	Compatibility	Price
LH-1PR Polarizer Rotation Mount, 25.4 mm, 8-32 Thread, A-LINE	IMPERIAL	$158
M-LH-1PR Polarizer Rotation Mount, A-LINE, 25.4 mm Diameter, M4 Thread	METRIC	$158
RM25B Optic Rotation Mount, 25.4 mm, 2° Graduations, OpticsCage+	UNIVERSAL	$116
RSP-1T Optic Rotation Mount, 25.4 mm, Fine Adjust Knob, 8-32 and M4	UNIVERSAL	$291