TPX optics : buying guide

Due to it’s interesting optical properties, light weight and relatively good resistance TPX is experiencing more and more interest from photonics industry. Let’s learn more about this material and it’s applications.

TPX lens

What is TPX ?


TPX stand for Transparent Polymer X. It is a Mitsui registered Trade mark of Polymethylpentene (or PMP).  It can be used as raw material for polymer machining, plastic injection, extrusion or even in the form of thin film.

TPX shows good transparency for a very extensive range from the UV to the THz area. It shows also very good electric insulation properties, good resistance to moisture and heat.

Moreover Polymethylpentene is the lightest (see below details) of the polymers, and shows a stable a relatively low refractive index (low dispersion).


In below table you’ll find most common characteristics of TPX

Density833 kg/cm3lightest of all polymers, less than half lighter than PTFE
Melting point232°C
Vicat softening point168°C
Heat distortion T°127°C
Water absorptionless than 0.01 percentASTM-D570
Volume resistivity>10^16
Yield stress30 MpaASTM-D570
Rockwell Hardness83HRR scale
Transmitance94%**in the THZ area. See below curves for other wavelengths. Best THz transmission.
Refractive index1.463in the visible range, varies between 1.46 & 1.466 in the THz range

It is interesting to note that the material has been validated by FDA administration for food processing usage.

Moreover, as it is halogen free it is considered as an environment friendly material.

Which optical components are available in TPX ?

Polymethylpentene can be formed and polish into several kind of optical components :

! Since TPX is mainly used in THZ application where surface quality aspect is not very important, it is important to require high quality polishing if the component is to be used in the visible / UV range too.

Advantages to other THz optics

Other materials that my be used for THz applications, including HRFZ-Silicon, PTFE (Teflon), Z-cut quartz, COP, COC and Sapphire.

The advantage of TPX is better transmission in the THz vision, wider range of transmission (from UV to THz), lighter material.

Comparison chart of UV transmission of different polymers and glass.

TPX UV transmission

Outdoor usage of TPX optics is not recommended as it may lead to color change and quality deterioration

Different usage of TPX windows

As the optical transmission range is very extended from UV to THz, many applications can be found, here are the most commons :

  • TPX windows are often used in vacuum chambers as they can be used down to 10-9 mm.Hg.
  • Cryogenic products
  • Food processing
  • Medical apparatus
  • THz emitter and cameras
  • Research

How much do TPX optics costs?

Due to the complexity of it’s manufacturing and relatively limited production actors, TPX material is rather more expensive than other polymers.

Fortunately the material is rather easily processed and polished which helps keeping TPX optical components costs competitive, especially against HRFZ-Si and sapphire.

As each project, specifications and quantities are different it is better to contact THz optical components manufacturers for getting a price for a specific component.

Other ressources on optics: