Linear transmittance filters (LTF) are used for wavelength identification applications, employing a transmittance that changes linearly over a specified wavelength range. The LTF transmittance must be monotonic to provide a one-to-one correspondence between the filter transmittance and a given wavelength.

Iridian is experienced in the design and manufacture of custom linear transmittance filters. They feature low substrate-etalon ripple, custom slope and dynamic ranges with low linearity variation and a choice of wide or narrow transmission ranges..

Some examples of LTF’s are shown here:.

https://iridian.jp/product-category/telecom-filters/linear-transmittance/