High reflection (HR) coatings are used for light or laser beam manipulation and have very high reflection at specific wavelengths or designed spectral range at specific angle or angle range of incidence. Optida Co. offers several types of typical HR coatings and customized ones. The coating could be provided on customer substrates or our own.

 

 

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Optida Co. offers single wavelength HR coatings with better than 99.7% reflection at one or several narrow wavelength regions. They are relatively insensitive to small changes in angular incidence (5-10 deg), but large changes (e.g., 45 deg) significantly affect the performance.   Single wavelength HR coatings, optimized for other than normal incidence have slightly higher reflection for S polarization than P polarization, so target reflections for different polarizations should be known before designing the coating in order to get the optimal solution.   Optida Co. manufactures single wavelength HR coatings using e-beam evaporation and this ensures high laser-induced damage treshold LIDT ≥ 12 J/cm2 (at 1064 nm, 3.4 ns pulses, single shot, using the requirements of ISO 11254-2).

 

 

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Multiwavelength HR coatings have better than 99-99.7% reflection at several narrow wavelength regions. They are also sensitive to considerable changes in angular incidence (>10 deg) and have slightly higher reflection for S polarization compared to P polarization, if designed for non-normal incident angle.

 

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Broadband HR coatings are also all dielectric multilayer stacks, like single or multiwavelength HR coatings. However, different thicknesses of the layer pairs ensure much wider high reflection region, like 400-700 nm, 500-700 nm, 600-850 nm, 700-1100 nm, etc.   Broadband HR coatings are also sensitive to considerable changes (>10 deg) in incident angle. Coatings, designed for normal incidence usually have R>99%, while coatings designed for non-normal incident angle exibit R>97-98%. However, actual values could be better or worse, depending on width of high reflection range.   Broadband HR coatings are all dielectric and therefore superior to metallic coatings for reflectivity, durability, and laser damage resistance.

 

 

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Metallic HR coatings are very broadband and relatively insensitive to incidence angle.   Optida Co. Ltd offers aluminum, silver, gold based metallic coatings which have slightly different optical and physical properties. Metallic HR coatings can have protective dielectric layer, as well as additional dielectric mirror to enhance reflection in UV range, depending on requirements of application.   Typical reflectance curve of protected silver mirror is shown.