Longwave Pass (LWP) Thin Film Filter Coatings

Thin Film Coatings

Thin film coatings are extremely thin layers of materials (such as TiO2, SiO2, MgF2, gold, aluminum etc…), which can be applied to the surface of a substrate like glass, metal or germanium, to effect a change in its optical properties. Effects such as reflection, refraction, anti reflection and conductivity can be produced and modified by expert calibration of the number of layers and the respective thicknesses of the thin film coatings in relation to the incidental wavelengths of light.

Longwave Pass (LWP) Thin Film Filter Coatings

Reynard  Corporation provides thin film Longwave (or Long Wave) Pass Coatings  for commercial, aerospace and military applications. These Longwave  Pass (LWP) coatings can either be applied to the high quality optical  components and substrates that Reynard also supplies, or to  customer-provided substrates. Longwave Pass (LWP) filter coatings are  designed for wavelength selection; that is, to allow the transmission  of relevant longer wavelengths while blocking or reflecting shorter  wavelengths.

Examples of Filters with Longwave Pass (LWP) Filter Coatings

• Visible Longwave Pass Filters (LWP Filters – Visible): These  longwave pass (LWP) filters are designed to transmit wavelengths in the  visible range longer than 50% of the “cut on” values and reflect the  shorter wavelengths. Optimized for a zero degree angle of incidence,  the transmission rate for these longwave pass (LWP) filters is  typically above 85%, with a reflectance rate greater than 98%.  Applications for longwave pass filters include color control in color  separators or combiners.

• Infrared Longwave Pass Filter (IR LWP Filter) Coatings: These longwave pass (LWP) filters are designed to transmit wavelengths in the infrared range longer than 50% of the “cut on” values and to reflect the shorter wavelengths. Optimized for a zero degree angle of incidence, the transmission rate for these infrared longwave pass (LWP) filters is typically above 85%, with a reflectance rate greater than 98%.

Longwave  Pass (LWP) filter coatings can be engineered and supplied by Reynard  Corporation for all wavelengths, from UV (Ultraviolet) through the  Visible, IR (Infrared) and Far Infrared bands.

Longwave Pass (LWP) Coating Process

Our thin film coating facility has 21 vacuum chambers, ranging from an 18” bell jar to a 54” fully automatic box coater, all in a 4000 square foot Class 1000 clean room. Processes include electron beam, ion-assisted and resistance source deposition. We have the capability to coat virtually any size and shape up to and including substrates 50” in diameter.

Available substrates include:

• Alon
• BK-7 (borosilicate crown glass)
• Calcium Fluoride (CaF2)
• Fused Silica
• Germanium (GE)
• KRS5 ( Thallium Bromo-Iodide)
• Sapphire
• Magnesium Fluoride (MgF2)
• Silicon (Si)
• Zinc Selenide (ZnSe)
• Zinc Sulfide (ZnS)
• Or as provided by the customer.

Coating materials include:

• Copper (Cu)
• Gold
• Hafnium Oxide (HfO2)
• ITO (Indium Tin Oxide)
• Magnesium Oxide (MgO)
• Nickel (Ni)
• Silicon Monoxide (SiO)
• Silver
• Titanium Dioxide (TiO2)
• Tantalum Oxide (Ta2O5)
• Zirconium Oxide (ZrO2)
• And many more…

Custom Coating Services

At  Reynard, over 80% of our business is custom. Our Longwave Pass (LWP)  coatings can be engineered and customized for your particular  application, and in addition we have one of the largest and most  comprehensive selection of standard and stock precision optical  components in the world. Reynard Corporation is the leading global  supplier of optical components to the aerospace, commercial and  military markets. We take pride in meeting and exceeding our customers’  expectations in concept, design, engineering and fabrication.

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Reynard Corporation operates per Military Specification Mil-I-45208A.