Free space variable optical attenuator using frustrated total internal reflection with 70 dB dynamic range.

With the advance of high power laser systems, there is an increasing need to dim the corresponding light field power over larger dynamic ranges. The usual means to control the attenuation of directed light use optical filters or coatings with tailored reflectance and transmittance properties. They do not provide the variability that is often required in experiments. A system is reported here that demonstrated continuous variation of the transmittance over 70 dB, using frustrated total internal reflection.