What’s Optical Filters

What is an Optical Filter?

An optical filter transmits only incident light in a specific wavelength range (red light for example) and does not transmit light outside the range. Optical filters are widely applied to image devices familiar to us, such as cameras and projectors. Moreover, optical filters are used for a wide variety of optical devices, including microscopes and surveying instruments, and measuring devices to be installed on production lines of semiconductors and high-precision equipment.

1.ND Filter

An ND filter attenuates the amount of incident light in a certain wavelength range at a constant rate. ND filters are used to adjust the amount of incident light entering CMOS sensors. ND filters are indispensable components for iris modules to be mounted onto digital cameras and camcorders.

Generally, an ND filter is coated with a metal film, but we provide ND filters of low-reflection type, which suppress the surface reflection of light to meet applications in demand.

ND Filter

2.Band-pass Filter

A band-pass filter transmits only a specific wavelength range in the spectrum of light, and consists of non-absorbable dielectric films by making use of the principle of the Fabry-Perot interferometer. Band-pass filters are used for medical equipment, including analyzers to examine immune responses and blood testing equipment.

It is possible to design the center wavelength, half-value width, and blocking range of a band-pass filter according to the application, which will make it possible to attain narrow-band characteristics with a half-value width of 1.0 nm along with low-loss characteristics with a transmittance of 90% or over.

Usually, a band-pass filter blocks a certain wavelength range of light. A band-pass filter, however, used in combination with a blocking filter that makes use of a metal film and a color glass filter is able to block the entire wavelength range of light.

3.High-power Laser Mirror

A high-power laser mirror adopts a dielectric multilayer film for the reflective film, thus making it possible to reflect a specific wavelength of light highly efficiently. High-power laser mirrors are used for high-power laser devices, such as YAG laser cutting machines and YAG laser welding machines, and the high laser power and the surface accuracy of our high-power laser mirrors gain high popularity.

Our high-power lasers incorporate not only high-reflection specifications but also custom-made specifications, including half-mirror specifications. Furthermore, customers can specify the materials and shapes of substrates to meet particular laser wavelength and application requirements.

4.Optical Filter Block

The datacom market is growing fast with the rapid popularization of data communication services, including smartphones and cloud service.

Optical filter blocks and WDM band-pass filters are used for optical transceivers that serve as key components in this market.

We are developing CWDM filter blocks for 40 GbE applications and LAN-WDM filter blocks for 100 GbE applications.

Optical Filter Block