Thomas Keating can manufacture TPX (poly 4 methyl pentene-1) for THz components to order. We have purchased the business and manufacturing equipment of Yarsley, who were our suppliers until they decided to stop manufacturing the material. TPX is a useful THz material because it has the lowest refractive index of common substances at 1.46: It is low loss, though not quite as low as HDPE, say. It has the distinct advantage that is transmitting in the visible, allowing alignment of QO systems with visible light (say a HeNe Laser).
(Taken from "THE OPTICAL CONSTANTS OF SOME COMMON LOW LOSS POLYMERS BETWEEN 4 AND 40 CM-1", Jim Birch et al, DES 61, Feb 1981, National Physical Laboratory, Teddington UK.)
Losses at higher wavenumbers for a 9.5mm sheet are given here. In addition to manufacturing lenses in TPX, it forms the window in our THZ absolute power meters, where it is favoured over HDPE because it is more mechanically rigid. For more details, including available sizes, contact