Optical Coating

Optical coating is one of the most important specification for optical components, they are used to enhance the transmission, reflection, or polarization properties of an optical component. The general coating include Anti-reflective coating (AR coating), High reflective coating (HR coating), Partial reflective coating(PF coating), Polariztion Beamsplitter coating, Non-polariztion beamsplitter coating. MOK Optics has strong capability to offer various coating service according to customer’s design.

 

● Anti-Reflective coating

 

Single layer MgF2 AR coating

Magnesium Fluoride is probably the most widely used thin film material for optical coating. It’s applicable to the substrates with the refractive index from 1.45 to 2.4. their performance is not outstanding, but it can present at significant improvement of anti-reflection compareed to an uncoated surface. For this reason, this material acts as the most popular anti-reflection coating in visible spectrum, they are insensitive to the change of incident angle.

Typical coating:

R<2%@400-700nm, AOI=0°

R<3%@400-700nm, AOI=45°

 

Multilayer broadband AR coating

Compared with single layer MgF2 AR coating, multilayer broad band AR coating provides higher transmission for a wide band width. It’s ideal for wide wavelength range lasers, its performance is senstitive to the incident angle change.

Typical coating:

Ravg<0.5%@400-700nm, AOI=0°

R<1%@400-700nm, AOI=45°

 

Multilayer sharp V AR coating

This kind of AR coating provides lowest reflectance on a narrow band width. It can achieve a minium reflection of less than 0.1%. We can provide such coating with center wavelength from 250nm-2200nm. When selection a suitable multilayer AR coating, the center wavelength band and damage threshold must be given special attention.

Typical coating:

R<0.25%@1064nm, AOI=0°

R<0.5%@1064nm, AOI=45°

 

 

● High reflection coating

 

HR coating include Dielectric high reflection coatind and Metallic high reflection coating. Dielectric coating can achieve a high reflection and it is generally used in single wavelength or visible spectrum. Metallic coating reflectance is lower than dielectric HR coating, but they have wide spectrum range, it can cover near UV, Visible and near IR.

 

Typical dielectric coating:

R>99.8%@1064nm, AOI=0°

R>99%@400-700nm , AOI=0°

 

 

 

 

Metallic coating

Protective Aluminium coating (Ravg>87%@400-1200nm)

Enhanced Aluminium coating(Ravg>93%@400-1200nm)

Protected Silver coating(Ravg>95%@450-12000nm)

Protected Gold coating(Ravg>98%@2000-12000nm)

 

● Beamsplitter coating

 

Beamsplitters are used to split or combine beam of light. The most common types of beamsplitters are plate and cube. the coating include polarization beamsplitter coating and non-polarization beamsplitter coating.

 

Polarization beamsplitter coating can generate special high reflectance to S-polarization and high anti-reflection to P-polarization for laser application. It can achieve nearly 100% reflectance for S-polarization and 100% transmission for P-polarization.

 

Typical polarization beamsplitter coating:

Rs>99%@632.8nm, AOI=45°

Rp<5%@632.8nm, AOI=45°

 

Rs>99%@450-650nm, AOI=45°

Rp<5%@450-650nm, AOI=45°

 

Typical non-polarization beamsplitter coating:

 

T/R=50/50 ±10%@400-700nm, AOI=45°

|Tp-Ts|<10%, |Rs-Rp|<10%, AOI=45°