𝐓𝐨𝐝𝐚𝐲'𝐬 𝐊𝐍𝐎𝐖𝐋𝐄𝐃𝐆𝐄 𝐒𝐡𝐚𝐫𝐞 : 𝐔𝐧𝐝𝐞𝐫𝐬𝐭𝐚𝐧𝐝𝐢𝐧𝐠 𝐑𝐞𝐟𝐫𝐚𝐜𝐭𝐢𝐯𝐞 𝐈𝐧𝐝𝐞𝐱

𝐓𝐨𝐝𝐚𝐲'𝐬 𝐊𝐍𝐎𝐖𝐋𝐄𝐃𝐆𝐄 𝐒𝐡𝐚𝐫𝐞

𝐔𝐧𝐝𝐞𝐫𝐬𝐭𝐚𝐧𝐝𝐢𝐧𝐠 𝐑𝐞𝐟𝐫𝐚𝐜𝐭𝐢𝐯𝐞 𝐈𝐧𝐝𝐞𝐱

The refractive index (RI) of a polymer is the ratio of the speed of light in a vacuum to the speed of light through the polymer. It varies with frequency (and thus wavelength) of light. Typically, it is measured at well-defined spectral wavelengths; for example, the yellow sodium double emission at 589nm wavelength. As other properties, refraction indices are temperature dependent. RI of air and water are 1.0 and 1.31 respectively.


𝐓𝐡𝐫𝐞𝐞 𝐩𝐫𝐨𝐩𝐞𝐫𝐭𝐢𝐞𝐬 𝐨𝐟 𝐩𝐨𝐥𝐲𝐦𝐞𝐫𝐬 𝐚𝐫𝐞 𝐫𝐞𝐥𝐚𝐭𝐞𝐝 𝐭𝐨 𝐭𝐡𝐞𝐢𝐫 𝐫𝐞𝐟𝐫𝐚𝐜𝐭𝐢𝐯𝐞 𝐢𝐧𝐝𝐞𝐱:

Light rays change direction when they cross the interface from air to the polymer.

Light reflects partially from surfaces that have a refractive index different from that of their surroundings.

The dispersive effect due to the diversity of the wavelengths of the light, the bending effect being frequency dependent.

 

The lower the refractive index, the less the material bends the light, decreasing the focusing power, the reflective effect and the light dispersion. Therefore, the polymer of an optical plastic must possess lower value of refractive index.


𝐎𝐩𝐭𝐢𝐜𝐚𝐥 𝐏𝐥𝐚𝐬𝐭𝐢𝐜𝐬

It is because of versatility, processability, mechanical and chemical properties of Optical Plastics that they are being used in:

 

Lenses

Optical circuits

Optical fibers

Anti-reflective films and coatings

Optical adhesives

LCD displays

Waveguides

UV-reactive inks

Varnishes


𝐓𝐡𝐞 𝐦𝐨𝐬𝐭 𝐩𝐨𝐩𝐮𝐥𝐚𝐫𝐥𝐲 𝐤𝐧𝐨𝐰𝐧 𝐨𝐩𝐭𝐢𝐜𝐚𝐥 𝐩𝐥𝐚𝐬𝐭𝐢𝐜𝐬 𝐢𝐧𝐜𝐥𝐮𝐝𝐞 𝐩𝐨𝐥𝐲𝐦𝐞𝐫𝐬 𝐬𝐮𝐜𝐡 𝐚𝐬:

Polymethacrylates

Polyurethanes

Polycarbonates

Polystyrenes

Urethane-acrylates

 

𝐀𝐧𝐚𝐥𝐲𝐳𝐢𝐧𝐠 𝐑𝐞𝐟𝐫𝐚𝐜𝐭𝐢𝐯𝐞 𝐈𝐧𝐝𝐞𝐱 𝐨𝐟 𝐏𝐨𝐥𝐲𝐦𝐞𝐫𝐬

𝐏𝐨𝐥𝐲𝐦𝐞𝐫𝐬 𝐯𝐞𝐫𝐬𝐮𝐬 𝐎𝐭𝐡𝐞𝐫 𝐌𝐚𝐭𝐞𝐫𝐢𝐚𝐥𝐬


Shown below is the table representing RI of polymers and glass. This could be clearly seen from the table that silicon has the highest refractive index of the examined materials but compared to common glass, polymers are in the same refractive index range. 


source : SpecialChem


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