Custom Optical FiltersOptical filters are passive optical devices that consist of specialized optical coatings applied onto a substrate. The coatings modify the refractive index of the substrate, enabling them to reflect, transmit, or absorb incoming light depending on its wavelength. This quality is useful for various optical tools and systems, such as chemical analysis units and microscopes.

Optical filters are bachelor in many variations, each of which possesses singled-out characteristics that brand it suitable for particular applications. Below, we provide an overview of some of the different types available.

Absorptive Filters

Absorbent filters have coatings made from organic and inorganic materials. These materials enable the filter to absorb the undesirable wavelengths and transmit the desirable wavelengths. This design ensures that no energy is reflected back toward the low-cal source.

Dichroic Filters

In contrast to absorptive filters, dichroic filters—also called thin-film filters or interference filters—have coatings that enable them to reflect the undesirable wavelengths and transmit the desirable wavelengths. The thickness and properties of the coatings determine which wavelengths are reflected and which wavelengths are transmitted. These types of optical filters are highly accurate, enabling users to target a small range of wavelengths.

Notch Filters

Notch filters—also called ring-terminate filters or band-turn down filters—are designed to cake a specific frequency band (i.e., the stopband frequency range). Any wavelengths above or below this range are allowed to laissez passer through freely. These types of optical filters are ideal for applications involving the combination of two or more signals since they can help isolate out interference.

Bandpass Filters

In contrast to notch filters, bandpass filters are designed to block every frequency except for a small range. They are a combination of shortpass filters and longpass filters—filtering out any wavelengths that are as well short or too long. This cutoff range can be lengthened or narrowed by adjusting the number of layers in the filter.

Shortpass Filters

Shortpass filters are designed to transmit wavelengths below a set length adamant by the optical coating and substrate. Any wavelengths that are longer than that point are blocked. These types of optical filters are commonly used to isolate specific college regions of a broad spectrum and in conjunction with longpass filters for bandpass filtration applications. Typical applications include chemical assay systems.

Longpass Filters

Longpass filters are designed to transmit wavelengths above a set length adamant past the optical coating and substrate. Any wavelengths that are shorter than that point are blocked. Typical applications include fluorescent spectroscopy systems. Additionally, they are commonly used in conjunction with shortpass filters for bandpass filtration applications.

Thin-Film Optical Filter Solutions From Evaporated Coatings, Inc.

Desire to learn more about optical filters and how to choose the right one for your optical needs? Turn to the experts at Evaporated Coatings! We specialize in the supply of loftier-precision optical coatings. By helping customers select the correct coating and applying it to their substrates, we can make custom optical filters for about any application.

Check out our custom optical filters page to learn more than about our sparse-film blanket capabilities. To discuss your optical filter requirements with one of our squad members, contact us today.