Interferometric spatial switch for polarized or unpolarized light using liquid crystal

An interferometric process for spatially switching at least one externally derived beam of substantially coherent light comprising the steps of:

• dividing said externally derived light beam into a substantially identical constituent beam pair;
• providing liquid crystal pixel means to phase modulate at least one constituent beam of said constituent beam pair, said pixel means comprising at least one stage having at least one associated pair of substantially coplanar liquid crystal (LC) pixels each cooperating in response to predetermined control signals respectively applied thereto to respectively contribute a selected phase shift to each respective constituent beam of said constituent beam pair respectively passing through said associated pixel pair;
• whereby each pixel of said one pixel stage respectively contributes to the overall selected phase differential between said constituent beam pair passing therethrough;
• said pixel means further comprising another pixel stage being positioned in parallel relationship with said one pixel stage along a common axis, each of said pixel stages comprising cascading pixel stages having mutually corresponding associated pixel pairs, each respective corresponding pixel pair in said cascading pixel stages cooperating in response to predetermined control signals respectively applied thereto to respectively impart a selected incremental phase shift to each respective constituent beam of said constituent beam pair passing through said cascading pixel stages;
• whereby each corresponding pixel of said cascading stages respectively contributes to the overall selected phase differential between said constituent beam pair passing therethrough;
• controlling the pixel means sufficiently fast for selectively shifting the phase differential between said constituent beam pair;
• and
• combining along coincident collinear paths respective components of said constituent beam pair, said collinear paths being situated such that said combined components of said constituent beam pair mutually interfere to form a respective output beam directed along at least a selected one of first and second output axes according to the phase differential between said constituent beam pair.

An interferometric spatial switch for selectively directing a plurality of externally derived beams of substantially coherent light, said switch comprising:

• means for dividing said plurality of externally derived light beams into a corresponding plurality of substantially identical constituent beam pairs, said beam dividing means comprising an array of input collimating lenses situated to receive said plurality of externally derived light beams, the lenses of said lens array cooperating to form said plurality of constituent beam pairs;
• an optical phase modulating device optically coupled to said beam-dividing means to receive said plurality of constituent beam pairs, said phase modulating device having liquid crystal (LC) pixel means situated to shift phase of at least one constituent beam of respective ones of said plurality of constituent beam pairs, said pixel means being electrically controllable for selectively shifting the phase differential between respective ones of said constituent beam pairs, and wherein said pixel means comprises a spatial light modulator (SLM) having an array of individually controllable LC pixels patterned to receive respective ones of said plurality of constituent beam pairs from said input lens array;
• whereby predetermined LC pixels of said pixel array can individually and simultaneously provide a selected phase differential between each respective one of said plurality of constituent beam pairs;
• and
• an output unit optically coupled to receive constituent beam pairs passing from said phase-modulating device, said output unit having polarization-independent means for combining along coincident collinear paths respective components of said received constituent beam pairs, said collinear paths being situated such that said combined components of respective ones of said constituent beam pairs mutually interfere to form a plurality of output light beams directed along at least a selected one of first and second output axes, according to the respective phase differential imparted by said phase-modulating device.