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Glossary of Technical Terms

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Aluminum Reflective Mirrors

Aluminum films can have their durability and weatherproofing enhanced by an overcoat of a protective film composed of silicon monoxide (SiO) or magnesium difluoride (MgF2).
Ordinary aluminum reflective mirrors have a reflectance of about 90%, but higher reflectances can be obtained by stacking dielectrics in layers, like in aluminum enhanced-reflection films with peak reflectances of 94% or higher or ultra-high reflection films with peak reflectances of 97% or higher.

Thin-Films? What's Vacuum Coating?

Anti-Reflective Film

GEOMATEC's anti-reflective films are multilayer optical films designed and processed to reduce the reflectance of a substrate.
Anti-reflective films are designed to obtain a target wavelength range and transmittance based on the refractive index of the substrate. GEOMATEC fabricates these films by combining dielectrics with a variety of refractive indexes.

High-Transmission Coatings

Clear Heat

Clear Heat adds snow-melting and condensation-preventing features to shatter-proof polycarbonate resin windows.
Clear Heat was jointly developed with Toho Sheet & Frame Co., Ltd.

Products Developed by GEOMATEC

Coating Material

Coatings can be formed using metals, metal oxides, or a combination of different materials.

Decorative Film

GEOMATEC's long-cultivated thin-film processing technology makes possible new decorative films such as films with luxurious metallic sheens or color gradations, or films that change color with viewing angle, effects previously unattainable with conventional painting technology.

Thin-Films? What's Vacuum Coating?


Defrosters are used to prevent condensation on a surface or the attachment of frost and ice.
GEOMATEC's defrosters/transparent heaters use a transparent, electrically conductive layer to warm the desired surface.
A variety of substrates like glass or resin can be used, and substrates with curved surfaces can be processed as well.

Products Developed by GEOMATEC

Dichroic Mirror Filter

Dichroic mirror filters are a type of multilayer optical film that reflects, transmits, separates, or combines specific wavelengths or polarization components.
Dichroic mirror filters are used to bring high transmittance, high reflectance, or superior angular dependence to devices like liquid crystal projectors or optical pick-ups.

Dichroic Mirrors and Beam Splitters


A dielectric is a metal oxide or fluoride with a high relative permittivity (dielectric constant). In the field of thin films, dielectrics are materials used in applications such as optical coatings.

Optically Functional Films


By controlling the orientation of the ITO film during fabrication, GEOMATEC has engineered an ITO film with a flatness similar to that achieved by physical grinding.
By omitting the grinding process, scratches and residues inherent to the procedure can be avoided, allowing GEOMATEC to create cleaner ITO films.
The domain structure is also uniform, so a clean patterning edge can be obtained. Film stress is also low, and stress on the substrate can be minimized.


fθ Lens

fθ lenses are used in YAG laser processing devices for marking, opening holes, and cutting.
GEOMATEC has developed fθ lenses that track the diffraction limits of aberrations within the scanning area. GEOMATEC's compact, high-performance fθ lenses have bit diameters well suited to both detailed and extensive processing.

Optical Components for Lasers

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H to N

Strengthening Thin Films

The following three methods can be used to increase the strength of thin films:

  • Increasing substrate temperature during thin-film formation
    The strength of the thin film drastically increases when a certain temperature is exceeded during thin-film formation.
    Although the temperature differs according to factors such as the melting point of the coating substance, a rise of temperature scatters the atoms reaching the substrate over a wider area of substrate surface and fills in gaps in the film more thoroughly, resulting in a thin film with a higher density.
  • Combined use of the bombardment effect and ion assistance
    By exposing the substrate within plasma, the substrate surface is cleaned and the surface temperature increases, forming a film of higher strength.
  • Incorporating contact metals
    In cases where the substrate and film are less compatible and show low adhesion, a thin film that adheres well to both materials can be placed in between, resulting in an overall stronger film.

Thin-Films? What's Vacuum Coating?

ITO Film for Dye-Sensitized Solar Cells

Dye-sensitized solar cells require ITO films with high heat resistance.
GEOMATEC's high-durability transparent conductive ITO films can retain their low resistance even when heated to temperatures of over 500℃ in atmosphere.
Properties such as resistance, transmittance, substrate material, and size can all be specified. Anti-reflective coatings, compact TiO2 films, and grid electrodes can be added as required.

High-durability Transparent Conductive Films

ITO-Substituting ZnO

The ITO films used in flat panel displays (FPDs) contain indium (In).
Although progress can be seen in the recycling of ITO sputtering target materials to cope with the sudden increases in FPD production and the rising cost of indium, there is significant concern regarding supply, especially with the expected increase in demand for televisions in developing countries.
GEOMATEC continues its research and development of zinc oxide (ZnO), an indium alternative that exhibits excellent performance as a transparent electrode.

Zinc Oxide (ZnO) Transparent Conductive Films

Multilayer Optical Film

The dielectrics that make up our multilayer optical films are transparent and colorless, lacking a typical metal's reflectivity or light absorption. Using these layers in different combinations, from single sheets to stacks of dozens, it is possible to create a film with virtually any desired transmittance or reflectance.
While a normal glass substrate has a reflectance of 4% on one side, this can be reduced by the addition of a dielectric coat with a refractive index lower than that of glass.
It is the stacking of dielectrics with different refractive indexes that allows GEOMATEC's multilayer optical films to have such a range of transmittance and reflectance.

Optically Functional Films

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O to U

Reflecting Telescope

Reflecting telescopes use concave surface mirrors with metal reflective films that have been polished and shaped with high precision. No lenses are used in this type of telescope, so the aperture can be easily enlarged and bright images can be obtained without chromatic aberrations.
GEOMATEC accepts requests to recoat and reprocess the primary and secondary mirrors of this type of telescope.

Reflective Film

Reflective films are broadly classified into two types: those composed of metal films and those composed of dielectric films.
The low angular dependence of metal films and the great wavelength selectability of dielectric films mean they are often called upon to serve different applications and needs.

Reflective Film - Dielectric Films

By creating minutely detailed optical designs and stacking dielectric thin films with various refractive indexes, GEOMATEC can provide films capable of reflecting specific wavelengths.
The films can be designed to reflect or transmit a single wavelength or a range of wavelengths.
Dispersion, absorption, and loss of light can all be minimized, so high reflectance and high transmittance can be achieved.

Dichroic Mirrors and Beam Splitters

Reflective Film - Metal Reflective Films

Metal reflective films such as those in mirrors maintain their reflectance even when the angle of incidence changes.
When used in first-surface mirrors, metal reflective films can offer high reflectivity with no ghosting, providing highly reliable images.

Thin-Films? What's Vacuum Coating?

Transmittance and Reflectance Relative to Refractive Index

When light enters a boundary between substances with different refractive indexes, most of the light is transmitted (and refracted) and some is reflected. The transmittance and reflectance depend on the refractive index of the substance.

Dichroic Mirrors and Beam Splitters


After pressure is decreased to a high vacuum range and air and impurities are removed, an inert gas such as argon is introduced to the device in sufficient amounts for glow discharge, or about 1 to 0.1 Pa. While the inert gas is being introduced, voltage applied between the substrate and target (the coating substance) generates plasma.
Ions accelerate and violently collide with the negative-potential target, causing particles (atoms or molecules) of the target to burst out and sputter onto the substrate. The coating substance reaches the substrate with more than a hundred times the energy of particles in the vacuum deposition method, allowing the formation of a stronger, denser film. The entire process occurs without any change in the coating material's composition.

Thin-Films? What's Vacuum Coating?

Stress (Residual Stress in Films)

Residual stress refers to stress remaining within an object after an external mechanical load is eliminated, or after an uneven temperature distribution becomes even or enters a steady state different from the initial state.
Thin-films may be polished or ground to neutralize residual stress (by adjusting the flatness).


A thin film is literally a thin film. But while common films like aluminum foil and plastic wrap are indeed thin, thin films made with vacuum coating can be considered completely different.
In the world of vacuum coating, a thickness ranging from a few hundred angstroms to 5 micrometers is what makes a thin film.
Because of their extreme thinness, these films need to be formed on supportive substrates.

Thin-Films? What's Vacuum Coating?

Thin-Film Thermocouple

A thermocouple is a temperature sensor made of two conductors of different metals. Because the thermoelectric power of different metals always differs, the contact between the metals at two connection points generates a voltage based on the temperature differential, and current flows in a fixed direction.
GEOMATEC's thin-film thermocouple is formed on a polyimide film.
The thin-film thermocouple is an extremely thin and flexible temperature sensor no more than 55 μm thick even when combined with a protective film. The thin-film thermocouple is completely flat and can easily measure temperatures in gaps no wider than a strand of hair.

Products Developed by GEOMATEC

Transparent Conductive Film (ITO Film)

Because of their unique ability to conduct electricity while remaining transparent, transparent conductive films are used as electrodes in touch panels and displays for devices such as laptop computers, monitors, mobile phones, and smartphones.
ITO films are the most common type of transparent conductive film. GEOMATEC is researching alternative materials to replace indium, a raw material in ITO that is becoming prohibitively expensive.

Transparent Conductive Films - ITO and ZnO

Transparent Conductive Film for Capacitive Touch Panels

The transparent conductive films incorporated into capacitive touch panels require low resistivity, good etchability, and high reliability.
GEOMATEC uses its optical design techniques to deal with ITO pattern visibility in both projected and surface capacitive touch panels. The transparent conductive coating can be formed on both glass and films.

ITO Films for Capacitive Touch Panels

Transparent Conductive Film for Resistive Touch Panels

The transparent conductive films used in resistive touch panels are vital to the structure and features of the panels, greatly influencing properties such as image quality and glare reduction.
GEOMATEC's transparent conductive films can improve the touch features, lifespan, and transmittance of resistive touch panels.

ITO Films for Resistive Touch Panels

Ultrasonic Cleaning - The Importance of Cleanliness

To form a thin film of good quality on a substrate, the substrate and environment must remain free of all dust and contamination.
To accomplish this, ultrasonic cleaning equipment is used to clean the substrate.
An ultrasonic wave of 30 to 100kHz generated in a cleaning tank induces cavitation. Impurities like dirt or oil attached to the surface of the substrate can be removed with very high efficiency. With the right combination of cleaning materials, any of a wide variety of substrates can be cleaned this way.
The cleaned substrate is then dried and sent on to the coating process in a perfectly clean state.

Thin-Films? What's Vacuum Coating?

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V to Z


A vacuum is defined as "a state in which a specific space is filled with gas at a pressure lower than atmospheric pressure" (Japan Industrial Standards [JIS]). Vacuum deposition requires a vacuum of 10-2 to 10-3 Pa, while sputtering requires a vacuum of 1 to 0.1 Pa. In vacuum deposition, the vacuum state prevents the inhibition of film formation by protecting the heated and evaporated coating materials from being oxidized by air or colliding with molecules within air before reaching the substrate.

Thin-Films? What's Vacuum Coating?

Vacuum Deposition

In vacuum deposition, a manufacturer coats a substrate by heating a coating material and evaporating it near the substrate to be coated.
When a spoon or glass (substrate material) is placed near boiling water (coating substance), the steam clouds over the surface of the spoon or glass. In the vacuum deposition method, thin films are formed by the same phenomenon using carefully engineered coating materials.

Thin-Films? What's Vacuum Coating?

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