Polarization forming optical device and polarization beam splitter

Claim 2

A polarization forming optical device comprising: a polarization beam splitter for reflecting one of an s-polarization component and a p-polarization component of light to be emitted from a light source and transmitting the other; a prism reflecting surface for receiving one of a reflected light and a transmitted light from said polarization beam splitter and rotating a plane of polarization at 90 ° to obtain a reflected light component; and means for deflecting the light advancing from said polarization beam splitter to said prism reflecting surface, the reflected light component from said prism reflecting surface, and/or the other of said reflected light and said trasmitted light from said polarization beam splitter, so as to make an advancing direction of an outgoing light based on said reflected light from said polarization beam splitter coincident with an advancing direction of an outgoing light based on said transmitted light from said polarization beam splitter; wherein said prism reflecting surface comprises a plurality of reflecting mirror surfaces, adjacent ones of which are perpendicular to each other, said reflecting mirror surfaces being arranged in rows in a direction perpendicular to a ridgeline formed between said adjacent reflecting mirror surfaces, said direction of arrangement of said rows of said reflecting mirror surfaces being inclined at 45 ° with respect to said plane of polarization of the incident light on said prism reflecting surface.

Claim 3

A polarization forming optical device as defined in claim 1, wherein said light source comprises a beam light source for emitting a random polarized light; first and second polarization beam splitters are laid on an optical axis of said beam light source; said first and second polarization beam splitters have reflecting surfaces inclined at 45 ° with respect to said optical axis of said beam light source and inclined at 90° with respect to each other; and said prism reflecting surface is located behind said first and second polarization beam splitters so as to perpendicularly intersect said optical axis of said beam light source; whereby assuming that Y-axis is parallel to said optical axis of said beam light source; X axis is perpendicular to said Y-axis; X-Y plane is perpendicular to each said reflecting surface; and Z-axis is perpendicular to said X-Y plane, a light beam of said random polarized light from said beam light source is converted into a linear polarized light having a plane of polarization parallel to said X-Y plane to obtain a light beam outgoing in a direction parallel to said X-axis.

Claim 4

A polarization forming optical device as defined in claim 1, wherein said light source comprises a beam light source for emitting a random polarized light; a single polarization beam splitter is laid on an optical axis of said beam light source; a reflecting mirror is laid on said optical axis of said beam light source; said polarization beam splitter has a reflecting surface inclined at 45 ° with respect to said optical axis of said beam light source; said prism reflecting surface is located so that the reflected light from said reflecting surface of said polarization beam splitter enters perpendicularly to said prism reflecting surface; and said reflecting mirror is inclined at 45° with respect to said optical axis of said beam light source and inclined at 90° with respect to said reflecting surface of said polarization beam splitter; whereby assuming that Y-axis is parallel to said optical axis of said beam light source; X-axis is perpendicular to said Y-axis; X-Y plane is perpendicular to both said reflecting surface and said reflecting mirror; and Z-axis is perpendicular to said X-Y plane, a light beam of said random polarized light from said beam light source is converted into a linear polarized light having a plane of polarization parallel to X-Z plane to obtain a light beam outgoing in a direction parallel to said X-axis.

Claim 5

A polarization forming optical device as defined in claim 1, wherein said light source comprises a beam light source for emitting a random polarized light; a first polarization beam splitter is laid on an optical axis of said beam light source and a second polarization beam splitter is laid on an optical path of a reflected light beam from said first polarization beam splitter; said first and second polarization beam splitters have reflecting surfaces inclined at 45 ° with respect to an incident light beam thereon and inclined at 90° with respect to each other; and said prism reflecting surface is located so that the reflected light from said reflecting surface of said second polarization beam splitter enters perpendicularly to said prism reflecting surface; whereby assuming that X-axis is parallel to said optical axis of said beam light source; Y-axis is perpendicular to said X-axis; X-Y plane is perpendicular to each said reflecting surface; and Z-axis is perpendicular to said X-Y plane, a light beam of said random polarized light from said beam light source is converted into a linear polarized light having a plane of polarization parallel to X-Z plane to obtain a light beam outgoing in a direction parallel to said X-axis.

Claim 6

A polarization forming optical device as defined in claim 1, wherein said light source comprises a beam light source for emitting a random polarized light; a single polarization beam splitter is laid on an optical axis of said beam light source; said prism reflecting surface is laid on an optical path of a reflected light beam from said polarization beam splitter; a reflecting mirror is laid on an optical path of a transmitted light beam through said polarization beam splitter after reflected on said prism reflecting surface; said polarization beam splitter has a reflecting surface inclined at 45 ° with respect to an incident light beam thereon; said reflecting mirror is inclined at 45° with respect to an incident light beam thereon; said reflecting surface of said polarization beam splitter is inclined at 90 ° with respect to said reflecting mirror; and said prism reflecting surface is located so that the reflected light from said reflecting surface of said polarization beam splitter enters perpendicularly to said prism reflecting surface; whereby assuming that X-axis is parallel to said optical axis of said beam light source; Y axis is perpendicular to said X-axis; X-Y plane is perpendicular to each said reflecting surface; and Z-axis is perpendicular to said X-Y plane, a light beam of said random polarized light from said beam light source is converted into a linear polarized light having a plane of polarization parallel to X-Z plane to obtain a light beam outgoing in a direction parallel to said X-axis.

Claim 7

A polarization forming optical device wherein two of said device as defined in claim 4 are combined together in symmetrical relationship with respect to said X-Z plane recited in claim 4 so that two of said first polarization beam splitter recited in claim 4 are located adjacent to each other, and said beam light source recited in claim 4 is commonly provided for said two devices.

Claim 8

A polarization forming optical device wherein two of said device as defined in claim 5 are combined together in symmetrical relationship with respect to said X-Z plane recited in claim 5 so that two of said prism reflecting surface recited in claim 5 are located adjacent to each other, and said beam light source recited in claim 5 is commonly provided for said two devices.

Claim 9

A polarization beam splitter comprising two transparent plates and a polarizing film interposed between said two transparent plates, each of said transparent plates being formed on its outer side surface with a plurality of prism elements arranged in parallel rows, each of said prism elements having two adjacent surfaces inclined at 45 ° with respect to a normal to an inner side surface of each said trasparent plate and inclined at 90° with respect to each other.

Claim 10

A polarization beam splitter comprising two transparent plates and a polarizing film interposed between said two transparent plates, each of said transparent plates being formed on its outer side surface with a plurality of prism elements arranged in parallel rows, each of said prism elements having two adjacent surfaces inclined at 45 ° with respect to a normal to an inner side surface of each said trasparent plate and inclined at 90° with respect to each other.

Claim 11

A polarization beam splitter comprising a single trasparent plate, rectangular prism and a polarizing film interposed between an inner side surface of said transparent plate and a slant surface of said rectan ular prism, said transparent plate being formed on its outer side surface with a plurality of prism elements arranged in parallel rows, each of said prism elements having two adjacent surfaces inclined at 45 ° with respect to a normal to said inner side surface of said transparent plate and inclined at 90° with respect to each other.

Claim 12

A polarization beam splitter comprising a single trasparent plate, rectangular prism and a polarizing film interposed between an inner side surface of said transparent plate and a slant surface of said rectan ular prism, said transparent plate being formed on its outer side surface with a plurality of prism elements arranged in parallel rows, each of said prism elements having two adjacent surfaces inclined at 45 ° with respect to a normal to said inner side surface of said transparent plate and inclined at 90° with respect to each other.

Claim 13

A polarization forming optical device as defined in any one of claims 1 to 7, wherein at least one of said polarization beam splitters comprises said polarization beam splitter as defined in claim 8.

Claim 14

A polarization forming optical device as defined in any one of claims 1 to 7, wherein at least one of said polarization beam splitters comprises said polarization beam splitter as defined in claim 9.

Claim 15

A polarization forming optical device as defined in any one of claims 1 to 7, 10 and 11, wherein said prism reflecting surface is replaced by a combination of a 1/4 wave plate and a plane mirror.

Claim 16

A polarization forming optical device as defined in any one of claims 1 to 7, 10 and 11, further comprising a phase plate located before said prism reflecting surface.

Claim 17

A polarization forming optical device comprising: first and second polarization beam splitters inclined at 90° with respect to each other for reflecting one of an s-­polarization component and a p-polarization component of light to be emitted from a light source and transmitting the other; a 1/2 wave plate located at a position of a symmetrical plane between said first and second polarization beam splitters for rotating a plane of polarization of an incident light at 90 ° ; and two reflecting mirrors inclined at 90 ° with respect to each other for making an advancing direction of a transmitted light through each one of said first and second polarization beam splitters coincident with an advancing direction of a trasmitted light through said each one of polarization beam splitters after reflected on the other polarization beam splitter and then transmitted through said 1/2 wave plate.

Claim 18

A polarization forming optical device comprising: first and second polarization beam splitters inclined at 90° with respect to each other for reflecting one of an s-­polarization component and a p-polarization component of light to be emitted from a light source and transmitting the other; a 1/2 wave plate located at a position of a symmetrical plane between said first and second polarization beam splitters for rotating a plane of polarization of an incident light at 90 ° ; and two reflecting mirrors inclined at 90 ° with respect to each other for making an advancing direction of a transmitted light through each one of said first and second polarization beam splitters coincident with an advancing direction of a trasmitted light through said each one of polarization beam splitters after reflected on the other polarization beam splitter and then transmitted through said 1/2 wave plate.

Claim 19

A polarization forming optical device comprising: a polarization beam splitter for reflecting one of an p-­polarization component and an s-polarization component of light to be emitted from a light source and transmitting the other; a prism reflecting surface for receiving a reflected light from said polarization beam splitter and rotating a plane of polarization at 90 ° to obtain a reflected light component; and a prism for making an advancing direction of a transmitted light from said polarization beam splitter based on said reflected light component from said prism reflecting surface coincident with an advancing direction of a transmitted light from said polarization beam splitter based on an incident light directly from said light source; wherein said prism reflecting surface comprises a plurality of reflecting mirror surfaces, adjacent ones of which are perpendicular to each other, said reflecting mirror surfaces being arranged in rows in a direction perpendicular to a ridgeline formed between said adjacent reflecting mirror surfaces, said direction of arrangement of said rows of said reflecting mirror surfaces being inclined at 45 ° with respect to said plane of polarization of the incident light on said prism reflecting surface.

Claim 20

A polarization forming optical device comprising: a polarization beam splitter for reflecting one of an p-­polarization component and an s-polarization component of light to be emitted from a light source and transmitting the other; a prism reflecting surface for receiving a reflected light from said polarization beam splitter and rotating a plane of polarization at 90 ° to obtain a reflected light component; and a prism for making an advancing direction of a transmitted light from said polarization beam splitter based on said reflected light component from said prism reflecting surface coincident with an advancing direction of a transmitted light from said polarization beam splitter based on an incident light directly from said light source; wherein said prism reflecting surface comprises a plurality of reflecting mirror surfaces, adjacent ones of which are perpendicular to each other, said reflecting mirror surfaces being arranged in rows in a direction perpendicular to a ridgeline formed between said adjacent reflecting mirror surfaces, said direction of arrangement of said rows of said reflecting mirror surfaces being inclined at 45 ° with respect to said plane of polarization of the incident light on said prism reflecting surface.

Claim 21

A polarization forming optical device as defined in claim 15, wherein said light source comprises a beam light source for emitting a random polarized light; said polarization beam splitter comprises a mirror type polarization beam splitter laid on an optical axis of said beam light source; said prism comprises a prism formed plate located at a position where both said transmitted lights pass; said prism formed plate is a transparent plate having one surface formed with a plurality of prism elements arranged in parallel rows and having the other surface which is planar; each of said prism elements has two adjacent surfaces inclined at an angleϑ with respect to a normal to said planar surface of said prism formed plate and inclined at an angle 2ϑ with respect to each other, said prism elements having a refractive index n; said prism formed plate is located in such a manner that said planar surface faces said polarization beam splitter, and that a ridgeline of said each prism element is perpendicular to an incident light to said each prism element; and said angleϑ is related with an incident angle β of an incident light from said beam light source to said polarization beam splitter so as to satisfy the following equation (1). n sinα = sinβ n cos(α + ϑ ) = cosϑ      (1)

Claim 22

A polarization forming optical device as defined in claim 16, wherein said incident angleβ is 45° .

Claim 23

A polarization forming optical device as defined in claim 17, wherein said mirror type polarization beam splitter is replaced by a polarization beam splitter as defined in claim 8.

Claim 24

A polarization forming optical device as defined in claim 17, wherein said mirror type polarization beam splitter is replaced by a polarization beam splitter as defined in claim 9.

Claim 25

A polarization forming optical device as defined in any one of claims 15 to 19, wherein said prism reflecting surface is replaced by a combination of a 1/4 wave plate and a plane mirror.

Claim 26

A polarization forming optical device as defined in any one of claims 15 to 19, further comprising a phase plate located before said prism reflecting surface.

Claim 27

A polarization forming optical device comprising: a first prism for dividing light to be emitted from a light source into two light beams; a polarization beam splitter for reflecting one of a p-­polarization component and an s-polarization component of each of said two light beams and transmitting the other; a prism reflecting surface for receiving a reflected light from said polarization beam splitter and rotating a plane of polarization at 90 ° to obtain a reflected light component; and a second prism for making an advancing direction of a transmitted light from said polarization beam splitter based on said reflected light component from said prism reflecting surface coincident with an advancing direction of a transmitted light from said polarization beam splitter based on an incident light directly from said first prism; wherein said prism reflecting surface comprises a plurality of reflecting mirror surfaces, adjacent ones of which are perpendicular to each other, said reflecting mirror surfaces being arranged in rows in a direction perpendicular to a ridgeline formed between said adjacent reflecting mirror surfaces, said direction of arrangement of said rows of said reflecting mirror surfaces being inclined at 45 ° with respect to said plane of polarization of the incident light on said prism reflecting surface.

Claim 28

A polarization forming optical device comprising: a first prism for dividing light to be emitted from a light source into two light beams; a polarization beam splitter for reflecting one of a p-­polarization component and an s-polarization component of each of said two light beams and transmitting the other; a prism reflecting surface for receiving a reflected light from said polarization beam splitter and rotating a plane of polarization at 90 ° to obtain a reflected light component; and a second prism for making an advancing direction of a transmitted light from said polarization beam splitter based on said reflected light component from said prism reflecting surface coincident with an advancing direction of a transmitted light from said polarization beam splitter based on an incident light directly from said first prism; wherein said prism reflecting surface comprises a plurality of reflecting mirror surfaces, adjacent ones of which are perpendicular to each other, said reflecting mirror surfaces being arranged in rows in a direction perpendicular to a ridgeline formed between said adjacent reflecting mirror surfaces, said direction of arrangement of said rows of said reflecting mirror surfaces being inclined at 45 ° with respect to said plane of polarization of the incident light on said prism reflecting surface.

Claim 29

A polarization forming optical device as defined in claim 22, wherein at least one of said first prism and said second prism is replaced by a prism formed plate having one surface formed with a plurality of prism elements arranged in rows.

Claim 30

A polarization forming optical device as defined in claim 22 or 23, wherein said polarization beam splitter is a polarization beam splitter as defined in claim 8.

Claim 31

A polarization forming optical device as defined in any one of claims 22 to 24, wherein said prism reflecting surface is replaced by a combination of a 1/4 wave plate and a plane mirror.

Claim 32

A polarization forming optical device as defined in any one of claims 22 to 24, further comprising a phase plate located before said prism reflecting surface.

Claim 33

A polarization forming optical device comprising: a polarizing film for reflecting one of a p-­polarization component and an s-polarization component of light to be emitted from a light source and transmitting the other; a prism reflecting surface for receiving a reflected light from said polarizing film and rotating a plane of polarization at 90 ° to obtain a reflected light component; a reflecting mirror for changing an advancing direction of one of a transmitted light from said polarizing film based on said reflected light component from said prism reflecting surface and a transmitted light from said polarizing film based on an incident light directly from said light source in such a manner that both said transmitted lights intersect each other; and a prism for making advancing directions of both said transmitted lights intersected coincident with each other to synthesize both said transmitted lights; wherein said prism reflecting surface comprises a plurality of reflecting mirror surfaces, adjacent ones of which are perpendicular to each other, said reflecting mirror surfaces being arranged in rows in a direction perpendicular to a ridgeline formed between said adjacent reflecting mirror surfaces, said direction of arrangement of said rows of said reflecting mirror surfaces being inclined at 45 ° with respect to said plane of polarization of the incident light on said prism reflecting surface.

Claim 34

A polarization forming optical device comprising: a polarizing film for reflecting one of a p-­polarization component and an s-polarization component of light to be emitted from a light source and transmitting the other; a prism reflecting surface for receiving a reflected light from said polarizing film and rotating a plane of polarization at 90 ° to obtain a reflected light component; a reflecting mirror for changing an advancing direction of one of a transmitted light from said polarizing film based on said reflected light component from said prism reflecting surface and a transmitted light from said polarizing film based on an incident light directly from said light source in such a manner that both said transmitted lights intersect each other; and a prism for making advancing directions of both said transmitted lights intersected coincident with each other to synthesize both said transmitted lights; wherein said prism reflecting surface comprises a plurality of reflecting mirror surfaces, adjacent ones of which are perpendicular to each other, said reflecting mirror surfaces being arranged in rows in a direction perpendicular to a ridgeline formed between said adjacent reflecting mirror surfaces, said direction of arrangement of said rows of said reflecting mirror surfaces being inclined at 45 ° with respect to said plane of polarization of the incident light on said prism reflecting surface.

Claim 35

A polarization forming optical device as defined in claim 27, wherein said prism reflecting surface is replaced by a combination of a 1/4 wave plate and a plane mirror.

Claim 36

A polarization forming optical device as defined in claim 27, further comprising a phase plate located before said prism reflecting surface.

Claim 37

A polarization forming optical device comprising: first and second polarizing films arranged in perpendicular relationship with each other for perpendicularly reflecting one of a p-polarization component and an s-polarization component of light to be emitted from a light source and transmitting the other; a 1/2 wave plate located at a position of a symmetrical plane between said two polarizing films for rotating a plane of polarization of an incident light at 90 ° ; first and second reflecting mirrors arranged at symmetrical positions with respect to said 1/2 wave plate for changing an advancing direction of a first transmitted light through said first polarizing film after reflected on said second polarizing film and then transmitted through said 1/2 wave plate, and changing an advancing direction of a second transmitted light through said second polarizing film after reflected on said first polarizing film and then transmitted through said 1/2 wave plate, respectively, in such a manner that said first trasmitted light intersects a third transmitted light through said first polarizing film directly from said light source, and said second transmitted light intersects a fourth transmitted light through said second polarizing film directly from said light source; first and second prisms arranged at symmetrical positions with respect to said 1/2 wave plate for making advancing directions of said first and third transmitted lights coincident with each other to synthesize said first and third transmitted lights and making advancing directions of said second and fourth transmitted lights coincident with each other to synthesize said second and fourth transmitted lights, respectively; and means for making an advancing direction of an outgoing light from said first prism coincident with an advancing direction of an outgoing light from said second prism to synthesize both said outgoing lights.

Claim 38

A polarization forming optical device comprising: first and second polarizing films arranged in perpendicular relationship with each other for perpendicularly reflecting one of a p-polarization component and an s-polarization component of light to be emitted from a light source and transmitting the other; a 1/2 wave plate located at a position of a symmetrical plane between said two polarizing films for rotating a plane of polarization of an incident light at 90 ° ; first and second reflecting mirrors arranged at symmetrical positions with respect to said 1/2 wave plate for changing an advancing direction of a first transmitted light through said first polarizing film after reflected on said second polarizing film and then transmitted through said 1/2 wave plate, and changing an advancing direction of a second transmitted light through said second polarizing film after reflected on said first polarizing film and then transmitted through said 1/2 wave plate, respectively, in such a manner that said first trasmitted light intersects a third transmitted light through said first polarizing film directly from said light source, and said second transmitted light intersects a fourth transmitted light through said second polarizing film directly from said light source; first and second prisms arranged at symmetrical positions with respect to said 1/2 wave plate for making advancing directions of said first and third transmitted lights coincident with each other to synthesize said first and third transmitted lights and making advancing directions of said second and fourth transmitted lights coincident with each other to synthesize said second and fourth transmitted lights, respectively; and means for making an advancing direction of an outgoing light from said first prism coincident with an advancing direction of an outgoing light from said second prism to synthesize both said outgoing lights.

Claim 39

A polarization forming optical device comprising a polarizing portion and a light beam synthesizing portion, wherein: said polarizing portion comprises: a polarization beam splitter for reflecting one of a p-­polarization component and an s-polarization component of light to be emitted from a light source and transmitting the other; reflecting means for receiving a reflected light from said polarization beam splitter and rotating a plane of polarization at 90 ° to obtain a reflected light component; and a first prism formed plate having one surface formed with a plurality of prism elements arranged in rows for making an advancing direction of a transmitted light from said polarization beam splitter based on said reflected light component from said reflecting means coincident with an advancing direction of a trasmitted light from said polarization beam splitter based on an incident light directly from said light source to synthesize both said transmitted lights; and said light beam synthesizing portion comprises: a reflecting surface for reflecting at least one part of a synthesized light from said first prism formed plate; and a second prism formed plate having one surface formed with a plurality of prism elements arranged in rows for making an advancing direction of a reflected light from said reflecting surface coincident with an advancing direction of the other part of said synthesized light from said first prism formed plate to synthesize said reflected light and said other part.

Claim 40

A polarization forming optical device comprising a polarizing portion and a light beam synthesizing portion, wherein: said polarizing portion comprises: a polarization beam splitter for reflecting one of a p-­polarization component and an s-polarization component of light to be emitted from a light source and transmitting the other; reflecting means for receiving a reflected light from said polarization beam splitter and rotating a plane of polarization at 90 ° to obtain a reflected light component; and a first prism formed plate having one surface formed with a plurality of prism elements arranged in rows for making an advancing direction of a transmitted light from said polarization beam splitter based on said reflected light component from said reflecting means coincident with an advancing direction of a trasmitted light from said polarization beam splitter based on an incident light directly from said light source to synthesize both said transmitted lights; and said light beam synthesizing portion comprises: a reflecting surface for reflecting at least one part of a synthesized light from said first prism formed plate; and a second prism formed plate having one surface formed with a plurality of prism elements arranged in rows for making an advancing direction of a reflected light from said reflecting surface coincident with an advancing direction of the other part of said synthesized light from said first prism formed plate to synthesize said reflected light and said other part.

Claim 41

A polarization forming optical device as defined in claim 31, wherein said polarizing portion further comprises a reflector for conducting at least one part of an outgoing light from said polarization beam splitter to said first prism formed plate.

Claim 42

A polarization forming optical device comprising: two sets of said polarizing portion recited in claim 31; and a light beam synthesizing portion comprising a second prism formed plate having one surface formed with a plurality of prism elements arranged in rows for making advancing directions of outgoing light beams from said two sets of said polarizing portion coincident with each other to synthesize said outgoing light beams.

Claim 43

A polarization forming optical device as defined in claim 31 or 33, wherein said reflecting means is a prism reflecting surface comprising a plurality of reflecting mirror surfaces, adjacent ones of which are perpendicular to each other, said reflecting mirror surfaces being arranged in rows in a direction perpendicular to a ridgeline formed between said adjacent reflecting mirror surfaces, said direction of arrangement of said rows of said reflecting mirror surfaces being inclined at 45 ° with respect to said plane of polarization of the incident light on said prism reflecting surface.

Claim 44

A polarization forming optical device as defined in claim 34 further comprising a phase plate located before said reflecting means.

Claim 45

A polarization forming optical device as defined in claim 31 or 33, wherein said reflecting means is a combination of a 1/4 wave plate and a plane mirror.

Claim 46

A polarization forming optical device comprising a polarizing portion and a light beam synthesizing portion, wherein: said polarizing portion comprises: first and second polarization beam splitters for reflecting one of a p-polarization component and an s-­polarization component of light to be emitted from a light source and transmitting the other; a 1/2 wave plate located between said first and second polarization beam splitters for rotating a plane of polarization of an incident light at 90 ° ; and first and second prism formed plates each having one surface formed with a plurality of prism elements arranged in rows for making an advancing direction of a first transmitted light through said first polarization beam splitter after reflected on said second polarization beam splitter and then transmitted through said 1/2 wave plate coincident with an advancing direction of a second trasmitted light through said first polarization beam splitter directly from said light source to synthesize said first and second transmitted lights, and making an advancing direction of a third transmitted light through said second polarization beam splitter after reflected on said first polarization beam splitter and then transmitted through said 1/2 wave plate coincident with an advancing direction of a fourth transmitted light through said second polarization beam splitter directly from said light source to synthesize said third and fourth transmitted lights, respectively; and said light beam synthesizing portion comprises: first and second reflecting surfaces for reflecting at least one part of a first synthesized light from said first prism formed plate and reflecting at least one part of a second synthesized light from said second prism formed plate, respectively; and a third prism formed plate having one surface formed with a plurality of prism elements arranged in rows for making an advancing direction of a first reflected light from said first reflecting surface coincident with an advancing direction of a second reflected light from said second reflecting surface to synthesize said first and second reflected lights, and/or for making the advancing direction of said first reflected light from said first reflecting surface coincident with an advancing direction of the other part of said first synthesized light from said first prism formed plate to synthesize said first reflected light and said other part of said first synthesized light and making the advancing direction of said second reflected light from said second reflecting surface coincident with the other part of said second synthesized light from said second prism formed plate to synthesize said second reflected light and said other part of said second synthesized light.

Claim 47

A polarization forming optical device comprising a polarizing portion and a light beam synthesizing portion, wherein: said polarizing portion comprises: first and second polarization beam splitters for reflecting one of a p-polarization component and an s-­polarization component of light to be emitted from a light source and transmitting the other; a 1/2 wave plate located between said first and second polarization beam splitters for rotating a plane of polarization of an incident light at 90 ° ; and first and second prism formed plates each having one surface formed with a plurality of prism elements arranged in rows for making an advancing direction of a first transmitted light through said first polarization beam splitter after reflected on said second polarization beam splitter and then transmitted through said 1/2 wave plate coincident with an advancing direction of a second trasmitted light through said first polarization beam splitter directly from said light source to synthesize said first and second transmitted lights, and making an advancing direction of a third transmitted light through said second polarization beam splitter after reflected on said first polarization beam splitter and then transmitted through said 1/2 wave plate coincident with an advancing direction of a fourth transmitted light through said second polarization beam splitter directly from said light source to synthesize said third and fourth transmitted lights, respectively; and said light beam synthesizing portion comprises: first and second reflecting surfaces for reflecting at least one part of a first synthesized light from said first prism formed plate and reflecting at least one part of a second synthesized light from said second prism formed plate, respectively; and a third prism formed plate having one surface formed with a plurality of prism elements arranged in rows for making an advancing direction of a first reflected light from said first reflecting surface coincident with an advancing direction of a second reflected light from said second reflecting surface to synthesize said first and second reflected lights, and/or for making the advancing direction of said first reflected light from said first reflecting surface coincident with an advancing direction of the other part of said first synthesized light from said first prism formed plate to synthesize said first reflected light and said other part of said first synthesized light and making the advancing direction of said second reflected light from said second reflecting surface coincident with the other part of said second synthesized light from said second prism formed plate to synthesize said second reflected light and said other part of said second synthesized light.

Claim 48

A polarization forming optical device as defined in claim 31, 33 or 37, wherein said polarization beam splitter is a mirror type polarization beam splitter.

Claim 49

A polarization forming optical device as defined in claim 31, 33 or 37, wherein said polarization beam splitter is a polarization beam splitter as defined in claim 8.

Claim 50

A polarization forming optical device as defined in claim 31, 33 or 37, wherein said polarization beam splitter is a polarization beam splitter as defined in claim 9.

Claim 51

A polarization forming optical device comprising: a plurality of said polarizing portion recited in claim 31 and/or a plurality of said polarizing portion recited in claim 37 arranged in such a manner that first prism formed plates of adjacent ones of said polarizing portions are symmetrical with each other; and a light beam synthesizing portion comprising a second prism formed plate having one surface formed with a plurality of prism elements arranged in rows for making advancing directions of outgoing light beams from said polarizing portions coincident with each other to synthesize said outgoing light beams.

Claim 52

A polarization forming optical device comprising a light beam width reducing portion and a polarizing portion, wherein: said light beam width reducing portion comprises: a reflecting member for reflecting a part of light to be emitted from a light source; and a first prism formed plate having one surface formed with a plurality of prism elements arranged in rows for making an advancing direction of a reflected light from said reflecting member coincident with an advancing direction of the other part of said light from said light source to synthesize said reflected light and said other part; and said polarizing portion comprises: a polarization beam splitter for reflecting one of a p-­polarization component and an s-polarization component of a synthesized light from said light beam width reducing portion and transmitting the other; reflecting means for receiving a reflected light from said polarization beam splitter and rotating a plane of polarization at 90 ° to obtain a reflected light component; and a second prism formed plate having one surface formed with a plurality of prism elements arranged in rows for making an advancing direction of a transmitted light through said polarization beam splitter based on said reflected light component from said reflecting means coincident with an advancing direction of a transmitted light through said polarization beam splitter based on an incident light directly from said light beam width reducing portion to synthesize both said transmitted lights.

Claim 53

A polarization forming optical device comprising a light beam width reducing portion and a polarizing portion, wherein: said light beam width reducing portion comprises: a reflecting member for reflecting a part of light to be emitted from a light source; and a first prism formed plate having one surface formed with a plurality of prism elements arranged in rows for making an advancing direction of a reflected light from said reflecting member coincident with an advancing direction of the other part of said light from said light source to synthesize said reflected light and said other part; and said polarizing portion comprises: a polarization beam splitter for reflecting one of a p-­polarization component and an s-polarization component of a synthesized light from said light beam width reducing portion and transmitting the other; reflecting means for receiving a reflected light from said polarization beam splitter and rotating a plane of polarization at 90 ° to obtain a reflected light component; and a second prism formed plate having one surface formed with a plurality of prism elements arranged in rows for making an advancing direction of a transmitted light through said polarization beam splitter based on said reflected light component from said reflecting means coincident with an advancing direction of a transmitted light through said polarization beam splitter based on an incident light directly from said light beam width reducing portion to synthesize both said transmitted lights.

Claim 54

A polarization forming optical device as defined in claim 42, wherein said polarization beam splitter has a polarizing film spaced from said second prism formed plate, and said polarizing portion further comprises a reflecting member for conducting at least one part of an outgoing light from said polarization beam splitter to said second prism formed plate.

Claim 55

A polarization forming optical device as defined in claim 42, wherein said reflecting means is a prism reflecting surface comprising a plurality of reflecting mirror surfaces, adjacent ones of which are perpendicular to each other, said reflecting mirror surfaces being arranged in rows in a direction perpendicular to a ridgeline formed between said adjacent reflecting mirror surfaces, said direction of arrangement of said rows of said reflecting mirror surfaces being inclined at 45 ° with respect to said plane of polarization of the incident light on said prism reflecting surface.

Claim 56

A polarization forming optical device as defined in claim 44 further comprising a phase plate located before said reflecting means.

Claim 57

A polarization forming optical device as defined in claim 42, wherein said reflecting means is a combination of a 1/4 wave plate and a plane mirror.

Claim 58

A polarization forming optical device as defined in claim 42, wherein said polarization beam splitter is a polarization beam splitter as defined in claim 8.

Claim 59

A polarization forming optical device as defined in claim 42, wherein said polarization beam splitter is a polarization beam splitter as defined in claim 9.

Claim 60

A polarization forming optical device comprising a plurality of repeating units each identical with said device as defined in claim 43, wherein said plurality of repeating units are juxtaposed with said reflecting member recited in claim 43 eliminated.

Claim 61

A polarization forming optical device comprising: a light beam width reducing portion comprising first and second units each identical with said light beam width reducing portion recited in claim 42, which are juxtaposed in such a manner that two of said first prism formed plate recited in claim 42 are symmetrically arranged adjacent to each other; a semi-transparent mirror located at a position of a symmetrical plane between said two first prism formed plates; and a polarizing portion comprising first and second units each identical with said polarizing portion recited in claim 42, which are symmetrically arranged with respect to said semi-transparent mirror; wherein a transmitted light through said semi-­transparent mirror based on an outgoing light from said first unit of said light beam width reducing portion and a reflected light from said semi-transparent mirror based on an outgoing light from said second unit of said light beam width reducing portion are joined together to be conducted to said second unit of said polarizing portion, and a transmitted light through said semi-transparent mirror based on the outgoing light from said second unit of said light beam width reducing portion and a reflected light from said semi-transparent mirror based on the outgoing light from said first unit of said light beam width reducing portion are jointed together to be conducted to said first unit of said polarizing portion, so that advancing directions of outgoing light beams from said first and second units of said polarizing portion are made parallel to each other.