This manual introduces absorptive neutral density filters, including manufacturing methods, optical density calculation, transmission table and other information.
This document is a user's guide for Thorlabs absorptive neutral density filters (part number 6266-S01). Unlike metallic filters, these are manufactured using ionically colored Schott glass (NG4, NG9, and NG11) polished to specific thicknesses to control optical density. The filters provide a range of optical densities from 0.1 to 5.0 and feature constant transmission over a large spectral range, particularly in the visible spectrum.
The guide details the relationship between optical density and transmission, noting that density is additive for stacked filters. It also covers available forms, including unmounted filters and mounted versions with SM1 threads for use with Thorlabs lens mounting cells. Additionally, the document lists various accessories such as lens tubes, angled optic mounts, and filter wheels compatible with the system.
| Glass Types | NG4, NG9 and NG11 |
|---|---|
| Optical Density Range | 0.1 to 5.0 |
| Design Wavelength | 546nm |
| Transmission at D=5.0 | 0.001% |
It is determined by accounting for absorption within the material and reflections on the polished surfaces.
Yes, optical density is additive, and mounted filters can screw together to achieve a desired density.