Refractive index database

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Optical constants of (C6H12)n (Polymethylpentene, PMP)
Smith and Loewenstein 1975: n,k 29.4–200 µm

Wavelength: µm

Complex refractive index (n+ik)[ i ]

n   k   LogX   LogY   eV

Derived optical constants


Manufactured by Imperial Chemical Industries under the name TPX.


D. R. Smith and E. V. Loewenstein. Optical constants of far infrared materials. 3: plastics, Appl. Opt. 14, 1335-1341 (1975)


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Polymethylpentene, (C6H12)n (PMP)

Polymethylpentene (PMP, (C6H12)n) is a thermoplastic polymer known for its high transparency, low density, and remarkable resistance to chemicals, particularly acids and alkalis. Due to its excellent clarity and ability to transmit ultraviolet and infrared light, it is often used in optical applications. PMP has a low moisture absorption rate, making it ideal for use in environments where dampness or humidity is a concern. It's also resistant to high temperatures, with a melting point around 230°C. Typical applications of PMP include lab equipment, electrical components, microwave cookware, and gas-permeable packaging. In the optics field, its refractive index and transmission properties can vary depending on the processing method and additives used. Overall, PMP combines the beneficial optical properties of glass with the ease of fabrication seen in plastics.

Other names

  • poly(4-methyl-1-pentene)


  • TPX (Mitsui Chemicals)

External links