Author Archives: Evaporated Coatings

  1. Why Notch Filters Are Essential in The Coating Industry

    Leave a Comment

    Notch filters, otherwise known as band-rejection or band-stop filters, are a type of optical filter designed to selectively reject a wavelength band and transmit at both longer and shorter wavelengths. Notch filters are often used throughout the coating industry to create components for various technological and scientific applications such as raman spectroscopy, laser-based fluorescence instrumentation, protection from laser radiation, and more.

    Notch Filters in the Coating Industry

    Ion-assisted electron-beam deposition technologies are the most widely used in coating manufacturing. This method features numerous advantages, such as a high deposition rate and excellent stress quality. To create notch filters using this deposition technique, it’s important to consider layer thickness constraints. If the layer thicknesses are not too thick or too thin, it allows for more accurate control of the index of refraction and thickness. 

    Notch Filter Applications

    Notch filters are used across various applications that require the transmission of some wavelengths while others need to be reflected or blocked. For example, many types of spectroscopy use this type of filter to assess the rotational and vibrational characteristics of molecular and crystal structures. This is especially beneficial in assessing how molecular structures react in specific environments as well as identifying unknown substances, detecting drugs, and analyzing forensic evidence. 

    A crucial factor in determining a filter’s strength is optical density. These measurements help in the growth of a microorganism culture, measuring biomass concentration, and other analytical processes within the life science industry.

    Another application of notch filters is with optical communications systems. These systems use notch filters to block any distortion that happens in a light pathway. Notch filters are also used frequently for laser safety applications, including laser eye protection. Safety glasses are designed and coated to reject harmful laser wavelengths.

    Most notch filters offer up to 85% peak transmission. Notch filter designs are available for deposition onto polymers, fiber ends, semiconductor materials, crystals, glass, and other temperature sensitive materials.

    Notch Filter Coatings from Evaporated Coatings

    Notch coatings are effective in transmitting some wavelengths while blocking others, making them suitable for a range of optical applications throughout various industries. At Evaporated Coatings, we manufacture notch filters with up to three rejection bands. Our design team can work with you to determine your specific requirements including incident medium, angle of incidence, optical density, steepness of cut on and cut off transitions, and transmission wavelength range. As experts in optical coatings, we can deliver a notch filter solution that meets the needs of your unique application.

    To learn more about our capabilities, or to get started on your custom notch filter solution, contact the experts at Evaporated Coatings today.

  2. What Are Neutral Density Filters?

    Leave a Comment

    A neutral density (ND) filter is a darkened glass affixed to a lens. This filter between the subject and the imaging tool reduces light wavelengths so that colors are not overexposed. ND filters only affect light, not color reproduction, sharpness, or contrast. We’ll explain in more detail how ND filters work, the various types of ND filters, and filter solutions by Evaporated Coatings.

    How Do Neutral Density Filters Work?

    Filtering the intensity of the colors of light that reach the imaging sensor allows operators better control over shutter speed and aperture selection. Thus, ND filters allow users to capture clear images in intense lighting conditions, yielding results that cannot be created through post-production editing. 

    Types of ND Filters

    Fixed ND filters, also called solid ND filters, have a coating equally distributed across the filter frame, producing a predetermined filter density. You can choose how dense you want the fixed ND filter to be depending on your imaging conditions. For instance, using a lighter density 3-stop filter allows you to set the shutter speed three times slower. 

    Variable ND filters feature two polarized filters working together, where one blocks a set amount of light while the other rotates so that the user can control the total amount of light let in at any given time.

    ND filters come in a wide range of polarization levels, from 2x, 4x, 8x, all the way up to 8192x. Each increase in multiplier corresponds to one f-stop, or one EV of light difference registered by the imaging tool. The polarization levels represent optical density (OD) and translate to different percentages of the original lens opening. For example, 2x means a 50% lens opening and 0.3 OD, 4x means a 25% opening and 0.6 OD, and 8x represents a 12.5% opening and 0.9 OD.

    Neutral Density Filters from Evaporated Coatings

    ND filters allow you to control how much light filters through your imaging tool. They enable better control over shutter speed and aperture settings, so you can create clearer images without affecting contrast, sharpness, or color.

    Evaporated Coatings, Inc. has been a leader in optical coatings for more than 60 years. We have maintained this position by innovating vacuum deposition technology and thin film processes. From design to preparation to coating, ECI brings technical knowledge, competitive pricing, and customized service to every client’s optical solution. Our product line covers a variety of optical coatings and substrates. For more information about our products and capabilities, contact us today.

  3. What Are Thin-Film Optical Filters?

    Leave a Comment

    Usually attached to a substrate like glass, thin-film optical filters are layers of materials with optical properties. These filters change the direction of light as it passes through them, creating internal interferences. Filters can be specially designed to transmit, reflect, or block light in any wavelength between ultraviolet (UV) and infrared (IR).

    Thin-film optical filters can be used for many optical applications, including astronomy, solar imaging, fluorescence microscopy, telecommunications, and remote sensing. This blog will discuss the mechanics of thin-film optical filters and their five main types.

    How Thin-Film Optical Filters Work

    To create a thin-film optical filter, we deposit the necessary coating onto the optical glass with extreme precision. One deposition method is ion-assisted e-beam evaporation. During this process, a beam of ions is directed at the substrate at the same time that the evaporated materials are being deposited onto the substrate. The ions contain energy that is released into the evaporative atoms of the materials, creating a thin film.

    Physical vapor deposition creates thin films by vaporizing solid material inside a vacuum and then depositing it onto the substrate. This type of deposition results in durable, scratch-resistant coatings. They can also withstand high temperatures.

    The specific thickness and number of coatings will affect the wavelength of light that passes through the filter. These methods, along with others, create durable coatings to achieve the intended optical effects. 

    Types of Thin-Film Optical Filters

    There are five main types of optical filters.

    1. Bandpass Filters. These filters transmit certain wavelengths and block out the surrounding light.
    2. Notch Filters. This type of filter blocks out a variety of wavelengths and transmits light on either side.
    3. Shortpass Edge Filters. Short wavelengths are transmitted through this filter, and longer wavelengths are blocked.
    4. Longpass Edge Filters. Long wavelengths are transmitted through this filter, while short wavelengths are blocked.
    5. Dichroic Filters. A dichroic filter reflects certain wavelengths while others pass through it.

    The first four filters are intended for use at 0° or other small angles of incidence. Dichroic filters are best used at 45° or less.

    Some of these types can be combined to create multiband filters. We can also create custom filters that have a different spectral shape than those listed above.

    Evaporated Coatings Inc.’s Thin-Film Optical Filters

    Evaporated Coatings Inc. has over 60 years of experience producing high-precision optical coatings. We have the expertise necessary to design and create thin-film optical filters that will solve your industry-specific problems. We are dedicated to staying up-to-date in the optical filter industry, as we develop our own thin-film designs and processes using advanced deposition methods.

    Our experienced engineering staff handles the entire process: design, preparation, and coating. We deliver personalized service to customers in the United States and around the world. Contact us to find out how we can meet your specific thin-film optical filter requirements.

  4. An Introduction to the Different Types of Optical Filters

    Leave a Comment

    Optical 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 available in many variations, each of which possesses distinct characteristics that make it suitable for particular applications. Below, we provide an overview of some of the different types available.

    Absorptive Filters

    Absorptive filters infographic 1Absorptive 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 light source.

    Dichroic Filters

    Dichroic filters infographic 2In 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 infographic 3Notch filters—also called band-stop filters or band-reject filters—are designed to block a specific frequency band (i.e., the stopband frequency range). Any wavelengths above or below this range are allowed to pass 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

    Bandpass filters infographic 4In 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 too 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 infographic 5Shortpass filters are designed to transmit wavelengths below a set length determined 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 higher regions of a broad spectrum and in conjunction with longpass filters for bandpass filtration applications. Typical applications include chemical analysis systems.

    Longpass Filters

    Longpass filters infographic 6Longpass filters are designed to transmit wavelengths above a set length determined by 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.

    Want 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 high-precision optical coatings. By helping customers select the right coating and applying it to their substrates, we can make custom optical filters for virtually any application.

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

  5. Design Guide for Thin Film Coatings

    Leave a Comment

    Design Considerations for Thin Film Coatings infographicThin film coatings, such as antireflective (AR) coatings, are made from various materials, such as metals, oxides, and compounds, and are deposited in layers onto a substrate. Thin film coatings can be deposited in both single and multiple layers, and the configuration you choose determines how it will manipulate different wavelengths of light.

    Thin film coatings have many different characteristics, which are used to improve or alter some element of the substrate’s capabilities. The design and configuration of thin film coatings heavily depend on performance requirements, and the proper design is crucial to the functionality and overall success of your application.

    Single Layer AR Coatings

    Single-layer AR coatings can have different refractive indices depending on the material. For example, single-layer AR coatings of magnesium-fluoride have a refractive index of 1.38. Applying the coating to a substrate with a 1.9 refractive index provides 0% reflection.

    Single-layer AR coatings of magnesium-fluoride can be adjusted to perform with various wavelengths and typically prevent reflection of 550 nm lasers. Single-layer AR coatings are prevalent, but complex applications may require multi-layer AR coatings.

    Double & Triple Layer AR Coatings

    Two or more AR coating layers can overcome the limitations of a single layer AR coating. Combining high and low index coatings, such as 2.3 and 1.38 produces a narrow bandwidth and close to 0% reflection. Three-layer coatings create a broadband AR coating using two high and a single low index coating, such as 2.1 and 1.38.

    Some substrates cannot achieve the necessary refractive index with a single coating. Multi-layer coatings allow manufacturers to use more available materials to block a more diverse range of incident angles and wavelengths. It is vital to consider the ideal materials when selecting a two or three-layer AR coating, as the refractive indexes available are limited and deposition is imperfect.

    Design Considerations for Thin Film Coatings

    When designing a configuration for thin film coatings, consider the following factors:

    • Thin film coatings offer increased performance at lower angles of incidence.
    • Longwave pass (LWP) filters allow for greater transmission and typically higher-performance than shortwave pass (SWP) filters. LWP filters enhance manufacturing tolerance and use more simple AR coatings.
    • Designing a coating with a greater than 2:1 bandwidth ratio increases the difficulty. It requires more layers and increases the percentage of reflection, with a higher reflection penalty when coating 30° and 45° angles of incidence.
    • For the most ideal design for manufacturing, consider materials that are 10nm or greater thickness.
    • Specify only necessary coating requirements. Performance is most optimal when requirements are specific and there is not a wide range.

    It is also necessary to consider the substrate texture. Substrates with lithography or etching require an AR coating with an approximate profile with a smaller height and width than the shortest wavelength.

    Single wavelength coatings are typically easier to manufacture compared to multiple wavelength coatings. Specific materials must be chosen for each wavelength, increasing the cost and complexity, especially when transmitting long and short wavelengths.

    Thin Film Coatings From Evaporated Coatings, Inc.

    When designing thin film coatings, such as AR coatings, films can be deposited in single and multiple layers to suit various substrates and applications. There are essential considerations when designing a thin film coating that will offer the performance you expect. At Evaporated Coatings, Inc., we are a leader in thin film coatings with over 60 years of experience in optical coating solutions. We can work with you to design and deposit custom AR coatings based on the needs of your application.

    For more information, or for help with your thin film coating design, contact us today. We also offer an eBook, called How to Determine Your Ideal Thin Film Coating Process, if you’d like to learn more about which thin film coating process might be right for you.

  6. Applications of Optical Microscopes

    Leave a Comment

    Optical microscopy is a technique that allows the viewing of samples more closely using optical microscopes. It relies on light and one or more lenses to magnify samples. Optical microscopy is remarkably versatile, increasing the detail and contrast of a microscopic specimen. A range of applications rely on simple and complex microscopy techniques.


    Fluorescence microscopy is a type of optical microscopy that uses a fluorescent dye called fluorophores. When light hits the dye, it induces fluorescence rather than scattering or absorbing light, making tissue, cells, and proteins visible under a microscope. Fluorophores absorb energy from a specific wavelength known as the excitement range resulting in the energy’s re-emission in a wavelength known as the emission range.

    Learn more about how we employ optical filters in fluorescence microscopy.

    Phase Contrast

    Applications of Optical Microscopes
    Click to expand
    Phase contrast is a form of optical microscopy that allows operators to view transparent specimens with enhanced contrast. Transparent samples, cells, and microorganisms are viewable in high-contrast without fixing or staining the samples. The technique allows viewers to see live specimens in their natural state.

    Differential Interference Contrast

    Differential interference contrast (DIC) introduces contrast to samples with minimal contrast using optical microscopy. It provides a near 3D appearance to the specimen, allowing viewers to see a contrasting image in high resolution. DIC uses infrared light for its long wavelengths, allowing the light to penetrate thick samples.

    DIC creates a contrasting image when light passes through a polarizing filter and another polarized optical device. The polarized light passes through an objective-specific prism where the light beam is split and passes through a condenser. The condenser focuses the beams of light on specific points of the specimen.

    The light beams pass through the specimen at various locations and various wavelengths. They move on to an objective lens that refocuses the beams on the rear of the focal plane. The nosepiece prism combines the beams, and the beam passes through the analyzer. The analyzer causes destructive and constructive interference, bringing the beams to the identical axis and plane. The light travels to the camera for the viewing of the DIC image.

    Brightfield and Darkfield Illumination

    Brightfield illumination presents a dark specimen on a bright background to create contrast. It is a simple technique that positions a light source below the sample. Light passes through the specimen to an objective lens and optical sensor. The darkness of the specimen increases with the specimen’s density. The more dense the sample is, the more pronounced the image will be.

    Brightfield illumination is the result of these four key elements:

    • Light Source
    • Condenser Lens
    • Objective Lens
    • Eyepiece or Camera

    Darkfield illumination creates a light specimen image on a dark background, contrasting the brightfield illumination technique. This technique enhances a specimen’s contrast without staining, allowing observation of living specimens.

    Darkfield illumination begins with a light source that is obstructed by a dark field patch stop as it enters the microscope. The light is reduced to a ring where the condenser lens focuses it onto the sample. When the light hits the specimen, it transmits or scatters. The objective lens permits scattered light but blocks transmitted light with help from the dark illumination block.

    Optical Microscopy Solutions From Evaporated Coatings

    Optical microscopy improves specimen viewing by magnifying microscopic samples and enhancing their visibility with techniques and lenses. Fluorescence, phase contrast, brightfield illumination, darkfield illumination, and DIC allow optical microscopes to deliver a closer image in various applications.

    At Evaporated Coatings, we specialize in high-quality optical coatings. We manufacture a range of optical filters, including excitement and emission filters for fluorescence microscopy. Our designers can help you find a cost-effective and high-performance solution, and our technicians use leading technology to manufacture the substrate and coatings you require. Contact us today to learn more about our high-quality optical coating solutions.

  7. Ion Beam Sputtering

    Leave a Comment

    Ion Beam Sputtering Coating (IBS) uses an ion source to deposit or sputter a thin film onto your targeted material to create a dielectric film. Since an ion beam is mono-energetic and collimated, it creates a very precise control over the thickness of the film. Since an ion beam is mono-energetic and collimated, it creates very precise control over the thickness of the film.

    A typical configuration of IBS systems includes the substrate, a target, and a gridded ion source, with the ion beam being focused on a target material, and a nearby substrate being the sputtered target material.

    What Is Ion Beam Deposition?

    IBS, otherwise known as ion beam deposition, is a process that deposits a thin film of dielectric or metallic material onto a substrate while allowing for extremely fine control over the coating thickness. During this process, an ion beam or source deposits, or sputters, material from a supply onto the workpiece in a dense, consistent pattern.

    Ion beam deposition processes are uniquely advantageous because operators can control everything from the sputtering rate to the ionic energy and density. This allows for complete control of the microstructure and film stoichiometry of the deposited layer. For applications that demand precision, such as with semiconductors, IBS outperforms alternative sputtering processes like physical vapor deposition.

    What Is Assisted Ion Beam Deposition?

    Assisted ion beam deposition uses two simultaneous processes — IBS and ion implementation — to create an intermixed coating. This process allows for a fine degree of control and can form gradually thickening or thinning transitions between the film layer and the underlying substrate’s original surface layer. Assisted ion beam deposition also gives the deposited film a much stronger bond.

    The Main Advantage of Ion Beam Sputtering Coatings

    One of the advantages of IBS is the control you get over several parameters. These include ion current density, ion energy, and the angle of incidence to help with the control of film microstructure. This is the main advantage and difference of sputtering processes, which makes IBS a great choice for any challenging applications you may have.

    Additional Benefits of IBS Coatings

    IBS coatings are known for providing precision control and high-density deposition layers. Other benefits of this coating method include:

    • High Energy Bonding. The IBS process provides enough kinetic energy to create a durable bond between the substrate’s surface and the coating.
    • Uniformity. Sputtering is typically emitted from a larger target surface area, ensuring a more uniform application when compared to vacuum coating and other alternative methods.
    • Versatility. IBS can provide a coating for nearly any material, even those with high melting points. This makes it an excellent choice for projects that require very particular coating properties.

    Ion Beam Sputtering Coatings From Evaporated Coatings

    At Evaporated Coatings, Inc., we specialize in providing high-quality optical coatings, AR coatings, depositions, and more. We work with each of our clients to select the right coating process based on each project’s budget, unique requirements, and intended applications. Contact us today to learn more about our design, preparation, and coating services, or visit this page to learn more about our IBS services.

  8. A Brief Guide to Thin-Film Optical Filters

    Leave a Comment

    What Are Thin-Film Optical Filters?

    Thin-film optical filters are optical devices consisting of alternating thin layers of specialized optical coatings deposited onto a substrate (e.g., optical glass). The coating layers alter the refractive index of the substrate, changing the direction of the various wavelengths in incoming light as it passes through one layer to the next. Either reflection, transmission, or absorption can occur depending on the wavelength(s) of the incoming light and the type of optical filter employed.

    Types of Thin-Film Optical Filters

    Thin-film optical filters are suitable for use with light in the ultraviolet (UV) to infrared (IR) wavelength range. They can be classified into five basic categories based on their spectral shape: bandpass filters, notch filters, shortpass edge filters, longpass edge filters, and dichroic filters. For more information on the various types available, check out this thin-film optical filter blog post.

    Applications of Thin-Film Optical Filters

    Thin-film optical filters are highly customizable, which allows them to be designed and built for effective performance in extremely specific or unique light-based applications. They are used across a wide range of industries in a variety of devices, equipment, and systems for many different use cases, including, but not limited to, the following:

    • Biological image detection. They can filter luminescence to facilitate the operation of biological imaging devices.
    • Chemical analysis. They can isolate specific emission or absorption ranges from incoming light to aid in chemical identification and analysis operations.
    • Contrast enhancement. They can increase the contrast between objects during scanning and other imaging operations to improve identification, recognition, and verification.
    • Laser systems. They can manipulate the beam of light generated in laser systems.
    • They can separate and modify signal transmissions in telecommunication systems.
    • Visible light coloring. They can add or enhance the hue of visible light to achieve a specific aesthetic effect.

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

    Thin-film optical filters find use in a variety of light transmission, blocking, and absorption applications. As their design and construction—i.e., the optical substrate and coating used—vary depending the application, some customers may find it challenging to select and source a product that meets their needs. Fortunately, the experts at Evaporated Coatings are here to help.

    At Evaporated Coatings, Inc., we specialize in the supply of high-precision optical coatings. Equipped with over 60 years of industry experience, we can help customers select the right coating and apply it to their substrates. Visit our custom optical filter page to learn more about our thin-film coating capabilities. If you want to discuss your optical filter requirements with one of our experts, contact us today.

  9. A Brief Guide to Beamsplitters

    Leave a Comment

    What Is a Beamsplitter?

    Click to expand

    What Is a Beamsplitter?

    Beamsplitters—also referred to as beam splitters or power splitters—are optical devices designed to split incident light into two or more separate beams. They can also be used in reverse to combine two or more separate beams into a single one.

    Some of the key properties to keep in mind when choosing a beamsplitter for an application include:

    • Splitting ratio: the amount of light that is transmitted vs. the amount of light that is reflected
    • Wavelength range: the finite range of wavelengths the device accommodates
    • Optical loss: the output power compared to the input power
    • Spatial configuration: how the output ports are positioned relative to the input beam
    • Aperture: the size of the area that allows light to enter the device

    How Does a Beamsplitter Work?

    As indicated above, beamsplitters are used to split incident light into two or more separate beams. The splitting process is dependent on the wavelength, intensity, or polarity of the incoming light and the design and configuration of the beamsplitter. Regardless of these factors, however, all beamsplitters follow the same basic principles: incoming light is split into two or more beams with one or more continuing forward through the optical component (i.e., transmitted) and one or more directed at an angle out of the optical component (i.e., reflected).

    Due to their ability to split light into separate beams based on controlled reflected/transmitted (R/T) ratios, beamsplitters find use in a wide range of light-based devices and equipment, including, but not limited to, the following:

    • Cameras and projectors
    • Fiberoptic systems
    • Head-up displays (HUDs)
    • Laser alignment and attenuation systems
    • Medical imaging systems
    • Sensors

    Types of Beamsplitters

    While all beamsplitters perform the same basic function—i.e., splitting light into separate beams—how they do so varies depending on their design. For example:

    • Standard beamsplitters split incident light without regard to the wavelength, polarization state, or intensity. They are generally used for one-way mirrors and illuminating assemblies and subassemblies.
    • Dichroic beamsplitters split incident light by wavelength. They are typically employed as laser beam combiners or broadband hot/cold mirrors.
    • Polarizing beamsplitters split incident light by polarization state. They are ideal for use in photonic instrumentation systems.
    • Non-polarizing beamsplitters split incident light by intensity. They are suitable for applications that utilize polarized light.

    Standard, dichroic, polarizing, and non-polarizing beamsplitters are available in a variety of configurations. Some of the most common include:

    • Cube beamsplitters. Cube beamsplitters consist of two right-angle prisms connected at the hypotenuse with a semi-reflective coating at the point of connection. They are suitable for applications that require simple mounting mechanisms and durable optical components.
    • Plate beamsplitters. Plate beamsplitters are made from flat and thin glass plate with a special coating on the first surface of the substrate. They are typically used for light with a 45-degree angle of incidence and can be built to support multiple incident ratios.
    • Pellicle beamsplitters. Pellicle beamsplitters are made from very thin substrates. This design allows for minimal beam offset.
    • Polka dot beamsplitters. Polka dot beamsplitters feature a pattern of reflecting dots on the glass surface. This design allows for geometrical beam splitting that is not angle-dependent.

    Custom Beamsplitter Coating Solutions From Evaporated Coatings, Inc.

    Beamsplitters serve a critical function in a wide range of light-based applications. Ensuring they operate as intended necessitates verifying the base substrate has the proper mechanical properties and utilizing the right optical coating. If you’re looking for an experienced and knowledgeable supplier for your beamsplitter coating needs, turn to the experts at ECI.

    At Evaporated Coatings, Inc. (ECI), we’ve supplied high-precision optical coatings for over 50 years. This extensive experience allows us to manufacture beamsplitter coatings for a wide range of R/T ratios, wavelength ranges, angles of incidence, polarization states, incident mediums, and temperature sensitivities and apply them to various customer-supplied substrates (e.g., glass, plastic, molded polymer, semiconductor materials, fibers, and fiber optic devices).

    Visit our beamsplitter page to learn more about our beamsplitter coating solutions. To discuss your beamsplitter requirements with one of our experts, contact us today.

  10. Thin-Film Optical Filters: An Overview

    Leave a Comment

    A thin-film optical filter is produced by placing thin layers of substances that contain specialized optical properties in an alternating fashion on top of a membrane; glass that made specifically for optical purposes, for example. As light passes through an optical filter, its wavelengths change directions as they pass through each layer of the filter. The thin-film coating alters the refractive indices, which results in internal interference, a process that helps to minimize interference from internal reflections. The wavelengths of light can pass through, absorbed, or reflect off of the filter. The kind of optical filter and the wavelength will determine how the light reacts to the filter.

    There are different types of optical filters. Some can transmit light, while others can reflect it, and still others can block it completely. All types can process any wavelength, from the UV range to the IR range. Generally, optical filters are categorized into five key groups according to the spectral shape of the filter.

    1. Bandpass filters. These optical filters transmit a variety of wavelengths while also blocking out the neighboring light.
    2. Notch filters. Notch optical filters block out a range of wavelengths while transferring the light on both sides.
    3. Shortpass edge filters. Optical filters that belong to this category transmit short wavelengths of light and block out longer ones.
    4. Longpass edge filters. Short wavelengths of light are blocked by longpass edge filters, while longer wavelengths are transmitted through them.
    5. Dichroic filters. Certain kinds of wavelengths are reflected by dichroic filters, while other ranges pass through them.

    Typically, edge, bandpass, and notch optical filters work at small angles of incidence (AOI), such as 0 degrees. Dichroic filters, however, are designed to work at an AOI of 45 degrees or larger and are designed in edge, bandpass, or notch arrangements.

    Multiband configurations of optical filters can also be made. Multiband optical filters are bandpass that allow multiple passband. These filters contain several blocking regions and they diffuse all neighboring wavelengths of light. Polychroic filters, for example, are dichroic filters that contain several notches or bands.

    While the majority of optical filters are grouped into the above mentioned categories, customized filters can be made. Custom filters can have any type of spectral shape you can think of; for instance, light waves from a xenon lamp can be made to resemble the spectrum of light the sun produces when passed through a customized filter. Other types of specially made optical filters can correspond with random spectral shapes.

    Since optical filters are so versatile, they can be used in a variety of ways, including:

    If you’re looking for any type of optical filter or coating then get in contact with Evaporated Coatings, Inc. today!

Request for Quote ECI will respond to your RFQ online form within 24 hours.
make a callCall Now