What Are Optical Filters?

An optical filter is a component that changes the light emission from a device. The filter transmits some portions of the optical spectrum while rejecting others; they are constructed utilizing differing materials and technologies depending on the intended filtering effect. 

There are a few common types of optical filters. Bandpass filters transmit a specific range of wavelengths while blocking others. Dichroic beamsplitters split a beam of light into two beams of different wavelengths. Notch filters transmit most wavelengths but block a narrow range. Edge filters transmit wavelengths that are longer or shorter than the edge wavelengths. 

cockpit nvis night vision

NVIS Filtering Components and MIL-L-85762 Compliance

During night missions, pilots need to be able to perceive outside objects with the use of night vision goggles (NVGs) to operate the aircraft safely. 

In these aerospace applications, filtering components are integrated into illuminated panels and light sources  inside the aircraft. The panels in an aircraft control the most critical elements of the aircraft, including heading, speed, altitude, and navigation. 

Cockpit lighting and devices that do not interfere with the functionality of NVGs are referred to as Night Vision Imaging System (NVIS) compatible, as they comply with MIL-L-85762. 

Cevians’ Filtering Components: Panel Types 4, 5, and 7 

optical filter

Cevians’ NVIS filtering components cater to the most common panels used in the aerospace industry: Types IV, V, and VII.

Type IV panels are one-piece panels with embedded incandescent lamps. They operate at 5 or 28 volts. These panels are not typically serviceable and need to be replaced when a failure occurs which translates to higher sustainment costs for platforms in the long run. Type IV panels are still in service today on legacy aircraft and have been replaced by Type V and VII panels.

Type V panels, which also operate at 5 or 28 volts, consist of an acrylic panel with a removable circuit board. These panels utilize incandescent lamps as Type IV panels do, although conversely they are soldered to the circuit board rather than embedded within the panel making them serviceable in the event of a failure.

Type VII panels consist of an acrylic panel and  an LED removable circuit board which operates at 5 or 28 volts. This panel type replaces outdated incandescent lighting technology with more efficient, ‘cool’ light sources and can be found on most new installations today.

With nearly four decades of experience, Cevians filtering components for lighting and sensors can be customized to meet a wide variety of industry needs, including ​​automotive, industrial, and medical applications. Our proprietary process uses moldable materials to customize shape and size, as well as a custom optical lens finish, and are highly heat resistant. 

Learn more about Cevians’ Filtering Components