Patent ID: 8346084

Claim:
A wavelength selective switch comprising: input and output ports; a light dispersing element optically coupled to the input and output ports; and a telecentric optical system including an optical switch for receiving wavelength components of an input light beam from the light dispersing element, altering the optical paths of the wavelength components of the input light beam, and directing the wavelength components of the input light beam to the light dispersing element after their optical paths have been altered, wherein the optical switch comprises a switching array, a first liquid crystal cell, a first lens assembly, a beam steering unit, a second lens assembly, a second liquid crystal cell, and a light reflecting element, the first lens assembly and the second lens assembly being positioned so that a distance between an input optical plane of the telecentric optical system and the first lens assembly and a distance between the first lens assembly and the beam steering unit are each equal to a focal length of the first lens assembly, and a distance between the beam steering unit and the second lens assembly and a distance between the second lens assembly and the light reflecting element are each equal to a focal length of the second lens assembly, and wherein the telecentric optical system further comprises a first lens having a first focal length, and a second lens having a second focal length, the first lens and the second lens having a coincident focal point, and the switching array being positioned at the coincident focal point.