Color selective light modulators employing birefringent stacks

A device for receiving at least partially polarized light having a polarization direction, comprising:

• a retarder stack comprising at least two retarders a of the retarders in the retarder stack comprise a first retarder that has a first orientation about the polarization direction and a first retardance, wherein said retarder stack receives said at least partially polarized light as input light and transforms said input light into transformed light having at least a first portion with a predetermined first spectrum and a first polarization and a second portion with a predetermined second spectrum and a second polarization;
• a modulator that receives at least some of said transformed light and outputs intermediate light, wherein said modulator is adapted to modulate said first portion of transformed light more than said portion of transformed light;
• and
• at least a second retarder having a second orientation about the polarization direction and having a second retardance for receiving said intermediate light and transforming said intermediate light into output light.

A device for receiving at least partially polarized light, comprising:

• a retarder stack comprising at least two retarders, wherein at least one of the retarders in the retarder stack comprises a first retarder that has a first orientation and a first retardance, wherein said retarder stack receives said at least partially polarized light as input light and transforms said input light into transformed light having at least a first predetermined first spectrum and a first polarization send a second portion with a predetermined second spectrum and a second polarization;
• a modulator that receives at least some of said transformed light and outputs intermediate light;
• and
• at least a second retarder having a second orientation and a second retardance that receives and transforms at least some of said intermediate light into output light, wherein said retarder stack, said modulator, and said second retarder are arranged such that said modulator has at least one state in which neither said first spectrum nor said second spectrum are modulated and has at least one state in which one of said at least first spectrum and second spectrum are modulated but not the other.

A device for manipulating a characteristic of at least partially polarized light, comprising:

• a retarder stack comprising at least two retarders, wherein at least one of the retarders in the retarder stack comprises a first retarder that has a first retardance and a first orientation with respect to a polarization direction of said at least partially polarized light, wherein said retarder stack receives the at least partially polarized light and outputs modified light having at least a first portion with a predetermined first spectrum and a first polarization and a second portion with a predetermined second spectrum and a second polarization;
• a modulator that receives an least some of the modified light and outputs intermittent light;
• and
• at least a second retarder that has a second retardance and a second orientation with respect to said polarization direction of said at least partially polarized light, that receives the intermittent light and outputs output light, wherein said first and second orientations are different, and said first retarder, said modulator, and said second retarder are arranged such that said modified light is not modulated by said modulator when said modulator is in one state but at least one of said first and second portions of said modified light is modulated by said modulator when said modulator is in another state.

A device, comprising:

• a retarder stack that receives input light and transforms said input light into transformed light having at least a first portion with a predetermined first spectrum and a first polarization and second portion with a predetermined second spectrum and a second polarization;
• a modulator that receives said transformed light and that outputs intermediate light;
• and
• at least a second retarder that receives at least some of said intermediate light and transforms said intermediate light into output light, wherein said retarder stack, said modulator, and said second retarder are arranged such that said modulator has at least one non-modulating state in which said transformed light and said intermediate light are approximately the same and at least one modulating state in which one of said first and second portions of said transformed light is modulated while the rest of said transformed light is not modulated.

A polarization manipulator for manipulating the polarization distribution of light, comprising;

• a retarder stack that receives the light and that outputs modified light;
• a polarization modulator that receives the modified light and outputs intermittent light;
• and
• at least one retarder that receives the intermittent light, manipulates the polarization distribution of the modified light, and outputs modified output light having at least a first portion with a predetermined first spectrum and a first polarization and a second portion with a predetermined second spectrum and a second polarization such that one of said first and second portions of said modified output light can be selectively filtered.

A device, comprising:

• a first retarder that receives input light and that transforms said input light into transformed light which includes a first portion with a predetermined first spectrum and a first polarization and a second portion with a predetermined second spectrum and second polarization;
• a modulator that receives said transformed light and that outputs intermediate light;
• and
• an output retarder stack that receives said intermediate light and that transforms said intermediate light into output light, wherein said first retarder, said modulator and said second retarder stack are arranged such that said modulator has at least one state in which neither said first portion nor said second portion are modulated and has at least one state in which one of said first portion and said second portion are modulated and the other is modulated differently.

A device, comprising:

• a first retarder stack that receives input light and that transforms sais input light into transformed light which includes a first portion with a predetermined first spectrum and a first polarization and a second portion with a predetermined second spectrum and a second polarization;
• a modulator that receives said transformed light and that outputs intermediate light;
• and
• an output retarder that receives said intermediate light and that transforms said intermediate light into output light, wherein said first retarder stack, said modulator and said output retarder are arranged such that said modulator has at least one state in which neither said first portion nor said second portion are modulated and has at least one state in which one of said first portion and said second portion is modulated and the other is modulated differently.

A device, comprising:

• a first retarder stack that receives input light and that transforms said input light into transformed light which includes a first portion with a predetermined first spectrum and a first polarization and a second portion with a predetermined second spectrum and a second polarization;
• a modulator that receives said transformed light and that outputs intermediate light;
• and
• a second retarder stack that receives said intermediate light and that transformed said intermediate light into output light, wherein said first retarder stack, said modulator, and said second retarder stack are arranged such that said modulator has at least one state in which neither said first portion nor said second portion are modulated and has at least one state in which one of said first portion and said second portion is modulated and the other is modulated differently.

A device, comprising:

• a first retarder stack that receives input light and that transforms said input light into transformed light which includes a first portion with a predetermined first spectrum and a first polarization and a second portion with a predetermined second spectrum and a second polarization;
• a modulator that receives said intermediate light and that outputs intermediate light;
• and
• a second retarder stack that receives said intermediate light and that transforms said intermediate light into output light, wherein said first retarder stack, said modulator, and second retarder stack are arranged such that said modulator has at least one non-modulating state in which said transformed light and said intermediate light are approximately the same and at least one modulating state in which a characteristic of one of said first portion and said second portion of said transformed light is modulated.

A polarization manipulator to modify a polarization distribution of light, comprising:

• a first plurality of retarders having respective first plurality of orientations .alpha..sub.N and a respective first plurality of retardances .GAMMA..sub.N, that manipulates the polarization distribution of the light to yield polarization manipulated light having a first portion with a predetermined first spectrum and a first polarization and a second portion with a predetermined second spectrum and a second polarization;
• a polarization modulating device that receives the polarization modified light and that outputs intermediate light, wherein said polarization modulating device is adapted to modulate said first portion of polarization manipulated light more than said second portion of polarization manipulated light;
• and
• a second plurality of retarders having a respective second plurality of orientations .alpha.'.sub.N and a respective second plurality of retardances .GAMMA.'.sub.N that receives and manipulates the polarization distribution of the intermediate light and that outputs modified output light having a modified polarization distribution for color selection.

A spectral filter for use with at least partially polarized light, comprising one or more white/filtered stages in series, each stage comprising:

• a modulator switchable between a first and second switching state, and having a modulation state, and having a modulation state of polarization and an isotropic state of polarization;
• a first retarder stack, positioned on a first side of said modulator, comprising two or more retarders, wherein the number, N, of said retarders and the retardances and orientations of said retarders are such that a first spectrum is transmitted in said modulation state of polarization and a second, complementary, spectrum is transmitted in said isotropic state of polarization;
• and
• a second retarder stack, positioned on the opposite side of said modulator, comprising N retarders, wherein the retardances and orientations of said retarders are such that in said first switching state said first and second spectra are transmitted in orthogonal states of polarization.

A spectral filter for use with polarized light, comprising one or more white/filtered stages in series, each stage comprising:

• a polarization modulator;
• a first retarder stack, positioned on a first side of said modulator, comprising N retarders, where N is two or more, said retarders having retardances .GAMMA..sub.1, .GAMMA..sub.2 . . . .GAMMA..sub.N and orientations .alpha..sub.1, .alpha..sub.2 . . . .alpha..sub.N ;
• and
• a second retarder stack, positioned on the opposite side of said electro-optic modulator, comprising N retarders, said retarders having retardances .GAMMA..sub.N . . . .GAMMA..sub.2, .GAMMA..sub.1 and orientations 90.+-..alpha..sub.N . . . 90.+-..alpha..sub.2, 90.+-..alpha..sub.1.

A polarization device to modify the polarization of an at least partially polarized light, comprising:

• a plurality of cascaded polarization manipulators, each including:
• a retarder stack comprising at least two retarders, wherein at least one of the retarders in the retarder stack comprises a first retarder that has a first orientation and a first retardance that receives an input light and that transforms the input light into transformed light having at least a first portion with a predetermined first spectrum and a first polarization and a second portion with a predetermined second spectrum and a second polarization;
• a modulator, coupled to said retarder stack, that receives the transformed light and that outputs intermediate light, wherein said modulator is adapted to modulate said first portion of transformed light more than said second portion of transformed light;
• and
• a second retarder, coupled to said modulator, having a second orientation and a second retardance that receives the intermediate light and that transforms the intermediate light into output light.

A polarization device to modify the polarization of an at least partially polarized light, comprising;

• a plurality of cascaded polarization manipulators, each including:
• a first plurality of retarders having a respective first plurality of orientations .alpha..sub.N and a respective first plurality of retardances .GAMMA..sub.N, that manipulates a polarization distribution of a portion of an input light to yield transformed light having a first portion with a predetermined first spectrum and a first polarization and a second portion with a predetermined second spectrum and a second polarization;
• a polarization modulating device, coupled to said first plurality of retarders, that receives the transformed light and that outputs intermediate light, wherein said polarization modulating device is adapted to modulate said first transformed light more than said second portion of transformed light;
• and
• a second plurality of retarders, coupled to said polarization modulating device, having a respective second plurality of orientations .alpha.'.sub.N and a respective second plurality of retardances .GAMMA.'.sub.N that receives and manipulates polarization distribution of a portion of the intermediate light and outputs light.

A device for receiving at least partially polarized light having a polarization direction, comprising:

• a first retarder stack comprising at least two retarders, including a first retarder and a second retarder, said first retarder having a first retardance and a first orientation with respect to the polarization direction of said at least partially polarized light, said second retarder having a second retardance and a second orientation with respect to the polarization direction of said at least partially polarized light;
• a modulator;
• and
• a second retarder stack comprising at least two retarders, including a third retarder having a third retardance and a third orientation with respect to the polarization direction of said at least partially polarized light, and a fourth retarder having a fourth retardance and a fourth orientation with respect to the polarization direction of said at least partially polarized light, wherein said first retarder, said second retarder, said modulator, said third retarder and said fourth retarder are optically coupled to each other and arranged such that said at least partially polarized light is transformed into output light having at least a first portion with a predetermined first spectrum and a first polarization and a second portion having a predetermined second spectrum and a second polarization.