Linear Variable Filter

2025.03.06

The linear Variable Filter (LVF) is a special optical filter whose transmittance or reflectivity changes linearly with changes in spatial position, such as in the direction of length or width. The design of this filter allows continuous spectral or intensity adjustment on a single element, resulting in a wide range of applications in a variety of optical systems.

Working principle

Linear gradient filters work based on their special coating or material structure, which is capable of producing linear changes in transmittance or reflectivity. For example, one side of the filter may allow a certain wavelength of light to pass through completely, while the other side blocks that wavelength almost completely, with the middle part gradually transitioning.

Performance parameter

长波通线性渐变滤光片	300-850nm
长波通线性渐变滤光片	900-1700nm
可见光短波通区域F	400-610nm
可见光短波通区域G	580-790nm
可见光短波通区域H	760-970nm
可见光短波通区域I	940-1150nm
可见光短波通区域J	390-1100nm
可见光短波通绿色波段	495-570nm

Peculiarity

·01 Linear change

The transmittance or reflectivity changes linearly with the position of the filter surface, which is the most significant feature of linear gradient filters.

·02 Spectral selection

It can be designed for specific spectral ranges, such as visible, ultraviolet or infrared light.

·03 Customizability

Depending on the application, parameters such as the linear variation range, starting and ending transmittance or reflectivity of the filter can be customized.

Application field

01 Imaging system

In imaging systems, linear gradient filters can be used to adjust the brightness or contrast of an image, or to image in a specific spectral range.

02 Spectral instrument

In spectral analysis, linear gradient filters can be used to splitter or select specific spectral components.

03 Optical measurement

In optical measurement, filters can be used to calibrate the response of a light source or detector, or to make precise measurements as part of an optical element.

04 Laser system

In laser systems, linear gradient filters can be used to adjust the intensity or spectral distribution of the laser.

Preparation technique

01 Ion beam sputtering

By bombarding the target with ion beam, the target atoms or molecules are sputtered out and deposited on the substrate to form a thin film. By precisely controlling the sputtering rate and the movement of the target, a linear gradient coating can be achieved.

02 Chemical vapor deposition

In a gaseous environment, the reactants are converted to solid products by chemical reactions and deposited on the substrate. The linear gradient deposition can be achieved by adjusting the concentration, temperature and flow rate of the reactants.

03 Laser interference coating

Using the principle of laser interference, periodic interference fringes are formed on the substrate, and the interference fringes are transformed into linear gradient filters by coating technology.

Sum up

Linear gradient filter is an optical element with unique properties and a wide range of applications. With the continuous development of science and technology, its application in optical systems will be more extensive and in-depth.

TEL