A device for processing an optical signal includes a refractor with a reflecting surface for reflecting the optical signal by total internal reflection. The device also includes a switchplate and an actuator to place the switchplate into proximal contact with the refractor to frustrate the total internal...http://www.google.com/patents/US5917641?utm_source=gb-gplus-sharePatent US5917641 - Frustrated total internal reflection device having a spacer and an endplate
