Collection: Neutral Density FIlter

Types of ND Filters

There are two primary types of ND filters:

• Absorptive ND Filters: These filters use a glass substrate to absorb light. They are available for various wavelength ranges, including visible and near-infrared (NIR) light. Absorptive filters are preferred because they do not reflect light back towards the source, which can interfere with the system setup.
• Reflective ND Filters: These filters use thin film optical coatings, often metallic, applied to a glass substrate. They reflect light back towards the source and are optimized for specific wavelength ranges. However, care must be taken to prevent the reflected light from interfering with the system.

Stacking Filters

ND filters can be stacked to achieve a custom optical density. The total OD of stacked filters is the sum of their individual OD values.

A Study Case for Selecting the Component

Example: Achieving a Specific Transmission

If you need to achieve a transmission of 0.5%, you would calculate the required OD as follows:OD=−log⁡(0.5%100%)=−log⁡(0.005)=2.3OD=−log(100%0.5%​)=−log(0.005)=2.3You could achieve this OD by stacking filters with OD values of 0.3 and 2.0, or 1.0 and 1.3.

Typical Applications and Why ND Filters are Used

Photography and Filmmaking

ND filters are crucial in photography and filmmaking for controlling light in bright conditions. They allow photographers to:

• Use wide-aperture lenses in bright light without overexposing the image, enabling a shallower depth of field.
• Achieve motion blur effects by using slower shutter speeds without overexposing the image.

Scientific Research

In scientific applications, ND filters are used to:

• Regulate the intensity of light sources to prevent overexposure or saturation of detectors.
• Ensure consistent light levels in experiments, which is particularly important in spectroscopy and imaging applications.

General Optical Systems

ND filters can be used in any optical system where light intensity needs to be controlled. They help in preventing overexposure, reducing glare, and maintaining optimal light levels for various optical instruments.By understanding and utilizing ND filters effectively, you can achieve greater control over light in a variety of applications, enhancing the quality and versatility of your optical systems.