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Glass Neutral Density filters attenuate light by absorption just like the gelatine neutral density filters. Glass ND Filters are more robust and tend to have more uniform absorption characteristics. They also attenuate by absorption and so care must be taken to avoid overheating. Attenuation is achieved by polishing glass to the correct thickness.

Knight Optical offers stock absorptive ND filters in 12.5mm and 25mm diameters, and 50x50mm squares manufactured from high quality glass. Each filter is available with blocking between 0.1 and 4.0 OD and are available to purchase direct from this page.

In addition to our stock absorptive glass ND filters, Knight Optical also offers an extensive custom optic service thanks to our many years of experience in the industry. We are able to supply ND filters cut to sizes and shapes to fit individual application and mount filters where applicable. For more information on our custom glass ND filters, or for more information on our entire filter range, contact our technical sales team.

Material:
Optical Density:
Diameter:
Length/Width:
Thickness:
Surface Quality:
Colour Glass
± 12.5% (@546nm)
+0/-0.2 mm
±0.2 mm
Varies between batches to control the OD
<60-40 scratch/dig

Mounting of diameters and squares.
Antireflective coatings can be applied to one or both faces for improved transmission.
Cutting down or edged to special shapes and sizes at short notice.
Available in sets, supplied in a wooden storage box for research and laboratory use.

47 Items

Name Density @ 546nm Transmission (%) @ 546nm Diameter (mm) Length (mm) Width (mm) Thickness (mm) Material/Equivalent Type Price Buy
FNG2588 0.054 88.28%@565nm 25 1.1 Absorptive Glass ND Filter
$18.35
FNG2584 0.076 84%@565nm 25 Absorptive Glass ND Filter
$18.35
FNG0113 pdf 0.1 79 12.5 0.6 NG11 Absorptive Glass ND Filter
$16.54
FNG0125 pdf 0.1 79 25 0.6 NG11 Absorptive Glass ND Filter
$25.92
FNG2572 0.13 72.4-74.4%@565nm 25 0.95 Absorptive Glass ND Filter
$18.35
FNG2571 0.15 71%@565nm 25 1.2 Absorptive Glass ND Filter
$18.35
FNG0213 pdf 0.2 63 12.5 1.4 NG11 Absorptive Glass ND Filter
$16.54
FNG0225 pdf 0.2 63 25 1.4 NG11 Absorptive Glass ND Filter
$25.92
FNG0250 pdf 0.2 63 50 50 1.4 NG11 Absorptive Glass ND Filter
$53.17
FNG6085 0.2 60 7 2 Absorptive Glass ND Filter
$6.95
FNG2554 0.26 54.6-56.6%@565nm 26 2.15 Absorptive Glass ND Filter
$18.35
FNG0313 pdf 0.3 50 12.5 2.3 NG11 Absorptive Glass ND Filter
$16.54
FNG2552 0.3 52 25 1 Absorptive Glass ND Filter
$18.35
FNG0325 pdf 0.3 50 25 2.3 NG11 Absorptive Glass ND Filter
$25.92
FNG3020 0.3 0.1 25 20 2.9 NG11 Absorptive Glass ND Filter
$53.17
FNG0350 pdf 0.3 50 50 50 2.3 NG11 Absorptive Glass ND Filter
$53.17
FNG0413 pdf 0.4 40 12.5 3.2 NG11 Absorptive Glass ND Filter
$16.54
FNG0425 pdf 0.4 40 25 3.2 NG11 Absorptive Glass ND Filter
$25.92
FNG0450 pdf 0.4 40 50 50 3.2 NG11 Absorptive Glass ND Filter
$53.17
FNG0513 pdf 0.5 32 12.5 4.1 NG11 Absorptive Glass ND Filter
$16.54
FNG0525 pdf 0.5 32 25 4.1 NG11 Absorptive Glass ND Filter
$25.92
FNG0550 pdf 0.5 32 50 50 4.1 NG11 Absorptive Glass ND Filter
$53.17
FNG0613 pdf 0.6 25 12.5 2.3 NG5 Absorptive Glass ND Filter
$16.54
FNG0625 pdf 0.6 25 25 2.3 NG5 Absorptive Glass ND Filter
$25.92
FNG0650 pdf 0.6 25 50 50 2.3 NG5 Absorptive Glass ND Filter
$53.17
FNG0813 pdf 0.8 16 12.5 3.1 NG5 Absorptive Glass ND Filter
$16.54
FNG0825 pdf 0.8 16 25 3.1 NG5 Absorptive Glass ND Filter
$25.92
FNG0850 pdf 0.8 16 50 50 3.1 NG5 Absorptive Glass ND Filter
$53.17
FNG1013 pdf 1 10 12.5 3.9 NG5 Absorptive Glass ND Filter
$16.54
FNG1025 pdf 1 10 25 3.9 NG5 Absorptive Glass ND Filter
$25.92
FNG1050 pdf 1 10 50 50 3.9 NG5 Absorptive Glass ND Filter
$53.17
FNP2799 1.1 27.2 2 Absorptive Glass ND Filter
$25.92
FNG1513 pdf 1.5 3.2 12.5 2.9 NG4 Absorptive Glass ND Filter
$16.54
FNG1525 pdf 1.5 3.2 25 2.9 NG4 Absorptive Glass ND Filter
$25.92
FNG1550 pdf 1.5 3.2 50 50 2.9 NG4 Absorptive Glass ND Filter
$53.17
FNG2013 pdf 2 1 12.5 3.8 NG4 Absorptive Glass ND Filter
$16.54
FNG2025 pdf 2 1 25 3.8 NG4 Absorptive Glass ND Filter
$25.92
FNG2050 pdf 2 1 50 50 3.8 NG4 Absorptive Glass ND Filter
$53.17
FNG2513 pdf 2.5 0.32 12.5 2.4 NG3 Absorptive Glass ND Filter
$16.54
FNG2525 pdf 2.5 0.32 25 2.4 NG3 Absorptive Glass ND Filter
$25.92
FNG2550 pdf 2.5 0.32 50 50 2.4 NG3 Absorptive Glass ND Filter
$53.17
FNG3013 pdf 3 0.1 12.5 2.9 NG3 Absorptive Glass ND Filter
$16.54
FNG3025 pdf 3 0.1 25 2.9 NG3 Absorptive Glass ND Filter
$25.92
FNG3050 pdf 3 0.1 50 50 2.4 NG3 Absorptive Glass ND Filter
$53.17
FNG4013 pdf 4 0.01 12.5 3.9 NG3 Absorptive Glass ND Filter
$16.54
FNG4025 pdf 4 0.01 25 3.9 NG3 Absorptive Glass ND Filter
$25.92
FNG4050 pdf 4 0.01 50 50 3.9 NG3 Absorptive Glass ND Filter
$53.17

47 Items

1

Absorptive Glass Neutral Density Filters

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Thickness (mm)
Density @ 546nm
Transmission (%) @ 546nm