WO2001020387A1

WO2001020387A1 - Beamsplitter device producting parallel output beams

Info

Publication number: WO2001020387A1
Application number: PCT/US2000/023481
Authority: WO
Inventors: Bradley A. Scott
Original assignee: Corning Inc
Current assignee: Corning Inc
Priority date: 1999-09-14
Filing date: 2000-08-25
Publication date: 2001-03-22
Anticipated expiration: 2002-03-14
Also published as: CN1390315A; AU7333400A; EP1214621A1; KR20020035600A; CA2385008A1

Abstract

A beamsplitter device for splitting an input beam of light having a plurality of components into a corresponding plurality of output light beams that each travel in a substantially parallel manner. In one embodiment, the beamsplitter device is configured as a polarizing beamsplitter device so as to split the input beam into separate polarization components by using a polarizing coating. Alternatively, in another embodiment, the beamsplitter device is configured as a wavelength filtering beamsplitter so as to split the input beam into separate wavelength components, by using a plurality of wavelength division multiplexing (WDM) coatings. The beamsplitter device comprises a planar transparent structural sheet or wall having substantially parallel first and second opposing surfaces. An input face portion receives the input beam and a plurality of output face portions transmit the output beams. A reflecting material internally reflects light within the sheet.

Description

BEAMSPLITTER DEVICE PRODUCTTNG PARALLEL OUTPUT BEAMS

Related Applications This application claims the benefit of U.S. Provisional Application No. 60/153,913, filed on September 14, 1999 and is hereby incorporated by reference in its entirety.

Background of the Invention

Field of the Invention

The present invention relates to light controlling devices and, in particular, relates to a beamsplitter device which divides an input beam of light having a plurality of non- identical components into a plurality of corresponding output beams that travel in substantially parallel directions.

Description of the Related Art

Beamsplitters are commonly used in science and industry to separate an input beam of light having a plurality of components into a corresponding plurality of output beams. In particular, some beamsplitters separate an unpolarized or partially polarized beam into linearly polarized output beams having orthogonal axes of polarization. Other beamsplitter devices are able to separate a polychromatic beam, or broadband beam, having a plurality of wavelength components into a corresponding plurality of substantially monochromatic output beams, or output beams having narrow spectral bandwidths.

However, neither type provides output beams that travel in substantially parallel directions. Thus, if parallel output beams are desired, an additional component which redirects one or more of the output beams is used. Since the additional component is separately mounted from the beamsplitter device, alignment is required, which may result in output beams having relatively poor parallelism.

For example, a polarizing beamsplitter cube is commonly used to convert an unpolarized input beam into separately directed linearly polarized output beams. In particular, the typical polarizing beamsplitter cube comprises a cube of transparent material that includes an input face and a first output face disposed along opposing external surfaces of the cube. The cube further comprises a second output face disposed along an external surface of the cube so as to be perpendicular to the first output face. The cube also has a polarizing coating disposed along an inner diagonal plane of the cube. Thus, if an input beam enters the input face in a perpendicular manner, the input beam strikes the coating at a 45 degree angle. At the 45 degree incident angle, the polarizing coating is adapted so that the p-component (i.e. the time varying component of the electric field vector parallel to the coating) of the input beam is transmitted through the coating and so that the s-component (i.e. the time varying component of the electric field vector of the input beam perpendicular to the coating) of the input beam is reflected by the coating at a 45 degree angle. The first and second output faces are disposed so that the p- component exits the first output face in a perpendicular manner and so that the s- component exits the second output face in a perpendicular manner. Consequently, the typical polarizing beamsplitter cube provides p-polarized and s-polarized output beams that travel in perpendicular directions. To provide parallel polarized output beams, first and second polarizing beamsplitter cubes are typically used. In particular, the first cube is used to provide perpendicularly directed p-polarized and s-polarized beams. The second cube is separately mounted from the first cube and positioned in the path of the s-polarized beam exiting the first cube such that the planes of the polarizing coatings of the first and second cubes are parallel to each other. The cubes are positioned so that the second output face of the first cube is parallel to the input face of the second cube. Consequently, the s-polarized beam is reflected by the polarizing coating of the second cube so that the p-polarized beam exiting the first cube and the s-polarized beam exiting the second cube are parallel to each other. Although the foregoing assembly of beamsplitter cubes provides generally parallel output beams, it usually does not provide the output beams with a high degree of parallelism. In particular, the parallelism of the output beams is primarily determined by the relative alignment of the cubes. Since the cubes are each individually mounted within an optical system, it may be difficult to precisely align the cubes with respect to each other. Furthermore, if either of the cubes are displaced with respect to each other by a relatively small amount, such as that which is caused by environmental influences such as vibrations and temperature variations, the parallelism may degrade to an unacceptably low level.

From the foregoing, it will be appreciated that there is a need for an improved beam splitting device that provides dissimilar output beams having a relatively high level of parallelism. In particular, there is a need for the device to provide output beams separated according to polarization or wavelength. Furthermore, there is a need for the device to maintain the high degree of parallelism in response to environmental influences.

Summary of the Invention The aforementioned needs are satisfied by the present invention which, according to one aspect, is a beamsplitter device for splitting an input light beam having at least first and second components into corresponding spatially separated first and second substantially parallel output light beams. The device comprises a transparent member comprising an input face having at least one input face portion and an output face having at least two output face portions. The input face portions are oriented to refract the input beam toward the first output face portion and the first output face portion is adapted to (a) transmit the first component of the input beam through the first output face portion so as to provide the first output beam and (b) reflect the second component of the input beam. The second output face portion is disposed to receive the second component of the input beam and adapted to transmit the second component of the input beam through the second output face portion so as to provide the second output beam. The face portions are oriented such that the first and second output beams are output in substantially parallel directions.

In one embodiment, the first and second components of the input beam are first and second polarization components and the first and second output beams are orthogonally polarized with respect to each other. In another embodiment, the first and second components of the input beam are first and second wavelength components and the first and second output beams have narrow spectral bandwidths.

In another aspect of the present invention, a polarizing beamsplitter device comprises a structural member comprising a transparent medium having first and second planar substantially parallel surfaces. The first surface refracts light so that an unpolarized input beam of light entering the first surface is directed toward the second surface. The second surface has an output portion with a material that (a) transmits a first polarization component of the input beam through the output portion so as to provide a first polarized output beam and (b) reflects a second polarization component to a reflecting material on the first surface. The reflecting material reflects the second polarization component of the input beam for refraction through the second surface so as to provide a second polarized output beam such that the first and second polarized output beams travel in substantially parallel directions.

In a further aspect of the present invention, a polarizing beamsplitter device comprises a structural member comprising first and second planar surfaces disposed in substantially parallel planes and a transparent medium disposed between the first and second surfaces. The device further comprises a polarizing coating disposed along a first portion of the second planar surface. The device is adapted so that an unpolarized input beam of light entering a first portion of the first planar surface is directed toward the polarizing coating. The polarizing coating transmits a first polarization component of the input beam so as to provide a first polarized output beam and reflects a second polarization component of the input beam toward a second portion of the first planar surface. The second polarization component reflects at the second portion of the first planar surface toward a second portion of the second planar surface. The second portion of the second planar surface transmits the second polarization component of the input beam so as to provide a second polarized output beam that travels in a direction which is substantially parallel to that of the first polarized output beam.

In yet another aspect of the present invention, a wavelength filtering beamsplitter device comprises a structural member comprising a transparent medium having first and second planar substantially parallel surfaces. The first surface refracts light so that an input beam of light having a plurality of wavelength components entering the first surface is directed toward the second surface. The second surface has a first and second output portion. The first output portion has material that (a) transmits a first wavelength component of the input beam through the first output portion so as to provide a first narrow-band output beam and (b) reflects a second wavelength component to a reflecting material on the first surface. The reflecting material reflects the second wavelength component of the input beam toward the second output portion. The second output portion transmits the second wavelength component so as to provide a second narrow-band output beam such that the first and second narrow-band output beams travel in substantially parallel directions.

From the foregoing, it should be apparent that the preferred embodiments of the beamsplitter device of the present invention are able to split an input light beam having first and second components into corresponding first and second output light beams that travel in substantially parallel directions. In particular, in one aspect of the invention, the beamsplitter device splits an unpolarized beam having first and second polarized components into first and second linearly polarized beams having orthogonal axes of polarization. Furthermore, in another aspect of the invention, the beamsplitter device splits a polychromatic input light beam having first and second wavelength components into corresponding first and second narrow-band output light beams. These and other objects and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.

Brief Description of the Drawings Figure 1 is a schematic drawing showing a side of a polarizing beamsplitter device, and illustrating an unpolarized beam entering the device and s-polarized and p-polarized output beams exiting the device in a substantially parallel manner;

Figure 2 is a schematic drawing showing a side of a polarizing beamsplitter system, and illustrating first and second unpolarized beams entering the device and first and second pairs of polarized output beams exiting the device;

Figure 3 is a schematic drawing showing a side of wavelength filtering beamsplitter device, and illustrating a polychromatic beam entering the device and a plurality of narrowband beams exiting the device in a substantially parallel manner;

Figure 4 is a schematic drawing showing a side view of another embodiment of the wavelength filtering beamsplitter device of Figure 3, and illustrating a polychromatic beam entering the device and a first plurality of parallel narrow-band beams exiting the device along a first directions and a second plurality of parallel narrow-band beams exiting the device along a second direction.

Detailed Description of the Preferred Embodiment

Reference will now be made to the drawings wherein like numerals refer to like parts throughout. As shown in Figure 1, a polarizing beamsplitter device 30 splits an unpolarized input beam 32 into first and second polarized output beams 34, 36 that travel in substantially parallel directions. The unpolarized input beam 32 travels through an exterior medium 38, such as air. and enters the device 30. The unpolarized input beam 32 generally comprises a combination of two linearly polarized components that have mutually perpendicular axes of polarization. Furthermore, as will be described in greater detail below, these components, otherwise referred to hereinbelow as the first and second polarized components, are substantially separated by the device 30 so as to provide the first and second orthogonally polarized output beams 34, 36. Moreover, the first output beam 34 having the first polarization and the second output beam 36 having the second polarization exit the device 30 along substantially parallel directions. As shown in Figure 1, the beamsplitter device 30 has an input face with an input face portion 40 and an output face comprised of at least two output face portions 42, 44. These faces are formed by a sheet of transparent material having a thickness T that provides structural rigidity. The sheet 46 includes first and second planar surfaces 48, 50 disposed in substantially parallel respective planes. The input beam 32 enters the input face portion 40 of the device 30 and undergoes refraction at a first refracting region 52 so as to provide a first refracted beam 60. The input beam 32 defines a first incident angle θi with respect to a line normal to the first surface 48 of the sheet 46. Furthermore, the first refracted beam 60 defines a first refracted angle θ₂ with respect the line normal to the second surface 50 according to the equation: n_oUtsinθι= n,_nsin θ (1) wherein n_oUt is the index of refraction of the exterior medium 38 adjacent the device 30 and n_ιn is the index of refraction of the sheet 46.

In one embodiment, the input face portion 40 comprises a first relatively thin antirefiective coating 62 disposed along the first refracting region 52 of the first surface 48. The purpose of the first antirefiective coating 62 is to enhance transmission of the input beam

32 through the first refracting region 52.

The first refracted beam 60 travels through the sheet 46 and enters a polarizing region 56 of the second surface 50 so as to define a second incident angle θ₃ with respect to a line normal to the second surface 50 of the sheet 46. Since the first and second surfaces 48, 50 of the sheet 46 are substantially parallel to each other, the second incident angle θ₃ is substantially equal to the first refracted angle θ₂.

The output face portion 42 comprises a polarizing coating 64 which is disposed along a polarizing region 56 of the second surface 50. The polarizing coating 64 transmits a linearly polarized beam having the first polarization that enters the .coating with the second incident angle θ₃. Furthermore, the polarizing coating 64 reflects a similarly directed second linearly polarized beam having the second polarization. In one embodiment, the polarizing coating 64 is adapted to transmit p-polarized light and reflect s-polarized light. Consequently, the first polarized component of the first refracted beam 60 exits the device 30 through the first output face portion 42 so as to provide the first polarized output beam 34 having the first polarization. In particular, the first output beam 34 exits the first output face portion 42 so as to define a first output angle φi with respect to a line normal to the second surface 50 of the wall 46 according to the equation: n_ιnsinθ₃= n_oUtsin φι (2)

Furthermore, according to equations (1) and (2) and the substantial equality of the angles θ₃ with θ₂, the first output angle φi is substantially equal to the first incident angle θ].

As shown in Figure 1, the second polarized component of the first refracted beam 60 reflects off of the polarizing coating 64 so as to provide a first reflected beam 66 having the second polarization that defines a first reflected angle θ with respect to the line normal to the second surface of the sheet. Furthermore, according to the law of reflection, the first reflected angle θ₄ is equal to the second incident angle θ₃.

As shown in Figure 1, the first reflected beam 66 travels through the sheet 46 to a reflecting coating disposed on a reflecting region 54 disposed along the first surface 48 of the sheet 46. The first reflected beam 66 defines a third incident angle θ₅ with respect to a line normal to the first surface 48 of the wall 46. Since the first and second surfaces 48, 50 of the wall are substantially parallel to each other, the third incident angle θ₅ is substantially equal to the first reflected angle θ . The first reflected beam 66 having the second polarization reflects off of the reflecting region 54 of the first surface 48 so as to provide a second reflected beam 68 having the second polarization that defines a second reflected angle θ₆ with respect to the line normal to the first surface 48 of the sheet 46. According to the law of reflection, the second reflected angle θ₆ is equal to the third incident angle θ₅. The second reflected beam 68 travels through the sheet 46 to the second output face portion 44 where it is inciderit on a second refracting region 58 of the second surface 50 of the sheet 46. The beam 68 defines a fourth incident angle θ with respect to the second surface 50 of the sheet 46. Since the first and second surfaces 48, 50 are substantially parallel to each other, the fourth incident angle θ is substantially equal to the second reflected angle θ₆. Consequently, the fourth incident angle θ is substantially equal to the first refracted angle θ₂

The second reflected beam 68 is refracted at a second refracting region 58 of the second surface 50 adjacent the second output face portion 44 so as to provide the second polarized output beam 36 having the second polarization. The output beam 36 exits the second output face portion 44 so as to define a second output angle φ with respect to a line normal to the second surface 50. In particular, the second output beam 36 is refracted according to the equation: n_ιnsinθ6= rioutsin φ₂ (3)

According to equations (1) and (3) and the substantial equality of the angles θ₆ with θ₂, the second output angle φ₂ is substantially equal to the first incident angle Q_\. Therefore, the output beams are substantially parallel to each other.

In one embodiment, the polarizing coating 64 is adapted to transmit p-polarized light having an axis of polarization that is parallel to the plane of the coating 64. Furthermore, the coating 64 is adapted to reflect s-polarized light having an axis of polarization that is perpendicular to the plane of the coating 64. In this embodiment, the first output beam 34 is p-polarized and the second output beam 36 is s-polarized.

In one embodiment, a known reflective coating 70 is disposed along the reflecting region 54 of the first surface 48 of the sheet 46 so as to provide a relatively high reflectivity. Consequently, most of the energy of the first reflected beam 66 is reflected into the second reflected beam 68. Furthermore, in one embodiment, a second antireflective coating 72 is disposed along the second refracting region 58 of the second surface 50. The purpose of the antireflective coating 72 is to inhibit reflection and enhance refraction at the second refracting region 58.

In one embodiment, the sheet 46 is comprised of substantially rigid glass, such as

BK7, manufactured by Schott Glass which is a German corporation, having an index of refraction approximately equal to 1.5. In particular, the sheet 46 is formed so that the first and second surfaces 48, 50 are parallel to within 0.5 seconds. As a result, the output beams 34, 36 are parallel to each other to within 0.75 seconds. Furthermore, since the wall 46 is substantially rigid, the high degree of parallelism of the output beams 34, 36 is substantially unaffected by external vibrations.

Thus, it will be appreciated that the polarizing beamsplitter device 30 provides many advantages when compared with polarizing beamsplitter devices known in the art. In particular, since the parallelism of the output beams 34, 36 is mainly determined by the parallelism of the first and second surfaces 48 and 50 of the sheet 46 and since the parallelism of prior art devices is determined by the alignment of separately mounted components, the device 30 is able to provide the output beams 34, 36 with a degree of parallelism which is substantially greater than that of prior art devices. Furthermore, the device 30 is able to realize such parallelism without requiring a complicated alignment procedure. Moreover, since the geometry of the device is substantially unaffected by external influences, the device 30 will always provide the output beams 34, 36 with substantially parallel directions. Additionally, the device 30 is bi-directional such that it can be used to create a plurality of output beams from one input beam and can also be used to combine a plurality of input beams into one output beam.

In one embodiment, the polarizing beamsplitter device 30 is used to provide a polarization converter assembly 31 that converts substantially unpolarized light into polarized light of the first polarization with a relatively high efficiency. In particular, the assembly 31 comprises the device 30 in combination with a polarization axis rotating device, such as a Yz wave retarder plate 74. More particularly, the plate 74 is positioned in the path of one of the output beams 34. 36 so as to align the axes of polarization of the output beams 34, 36.

For example, as shown in Figure 1. in one embodiment, the plate 74 is positioned in the path of the second output beam 36. The plate 74 rotates the axis of polarization of the second output beam 36 by ninety degrees without substantially changing the direction of travel of the second output beam 36. Consequently, the plate 74 provides the second output beam 34 with the first polarization. Thus, the device 30 in combination with the plate 74 is able to convert unpolarized light into light having the first polarization with substantially 100% efficiency. However, in another embodiment, it will be appreciated that the plate 74 could be positioned in the path of the first output beam 36 so as to provide both output beams with the second polarization.

Thus, it will be appreciated that the polarization converter assembly 31 converts unpolarized light into a pair of linearly polarized beams having substantially identical polarization. Furthermore, the assembly 31 provides the output beams 34, 36 that have a relatively small non-parallel deviation of approximately 1.5 seconds. Such parallelism is made possible by the polarizing beamsplitter device 30 which contributes only 0.75 seconds to the non-parallel deviation. Furthermore, since the plate 74 deviates the direction of the incident output beam by an amount that depends on the parallelism between external faces of the plate, the plate 74 contributes only 0.75 second to the non-parallel deviation of the output beams 34, 36.

Reference will now be made to Figure 2 which illustrates a polarizing beamsplitter system 80 in accordance with another aspect of the present invention. In particular, the system 80 comprises first and second polarizing beamsplitter devices 82, 84 formed from a common transparent sheet 86 so that the beam splitting devices 82, 84 are permanently aligned with each other. Otherwise, the devices 82. 84 are structurally and functionally identical to the devices of Figure 1. Thus, as shown in Figure 2. a first unpolarized input beam 88 entering a first input face portion 89 of the system 80 is split by the system 80 so that a first polarized output beam

90 having the first polarization exits a first output face portion 91 of the system 80 and so that a second output beam 92 having the second polarization exits a second output face portion 98 of the system 80. The first and second output beams 90, 92 travel in substantially parallel directions which are substantially aligned with the direction of the first input beam 89. A second unpolarized input beam 94 simultaneously entering a second input face portion 95 of the system 80 is split by the system 80 so that a third output beam 96 having the first polarization exits a third output face portion 97 of the system 80 and so that a fourth output beam 98 exits a fourth output face portion 99 of the system. The third and fourth output beams 96, 98 travel in substantially parallel directions which are substantially aligned with the direction of the second input beam 94.

Thus it will be appreciated that the polarizing beamsplitter system 80 provides many advantages. In particular, the system 80 is able to split two separate input beams into two corresponding pluralities of output beams. Furthermore, the first plurality of output beams are substantially parallel to the first input beam and the second plurality of output beams are substantially parallel to the second input beam even if the input beams are not parallel to each other.

Reference will now be made to Figure 3 which illustrates a wavelength filtering beamsplitter device 100 in accordance with another aspect of the present invention. The device 100 of Figure 3 receives an input beam 102 of light having a plurality of wavelength components. The device 100 provides a corresponding plurality of output beams 108 having spectral bandwidths that are substantially narrower than the combined spectral bandwidth of the input beam 102 such that the output beams exit the device 100 in a substantially parallel manner. In one embodiment, the output beams 108 are substantially monochromatic and each of the output beams 108 has a different wavelength.

As shown in Figure 3, the wavelength filtering beamsplitter device 100 is similar to the polarizing beamsplitter device 30 of Figure 1. In particular, the device 100 comprises a similar transparent structural sheet 106 having first and second parallel surfaces 108, 110.

The first surface 108 includes an input face portion 120 having a first refracting region 112 for receiving the input beam 102 and a reflecting region 1 14 adapted to internally reflect the input beam 102. However, instead of the polarizing region 56 and the second refracting region 58 of the device 30 of Figure 1, the second surface 110 of the device 100 has a plurality of wavelength filtering regions 116 adapted to provide band-pass transmission through a plurality of output face portions 124 of the device 100. Moreover, the regions 116 provide band-rejection reflection of the input beam 102 so that the input beam 102 is internally reflected within the sheet. As shown in Figure 3, in one embodiment, a plurality of known wavelength division multiplexer (WDM) coatings 118 are disposed along the second surface 110 of the wall 106 so as to provide the plurality of wavelength filtering regions 116 and the output face portions 124. In particular, each coating 118 is adapted to receive a light beam having a relatively wide spectral range and transmit a substantially narrow range of frequencies centered about a particular wavelength. Furthermore, the plurality of output face portions 124 of the device

100 are the external surfaces of the WDM coatings 1 18. Moreover, each WDM coating 118 is adapted to reflect the light that is not transmitted.

In one embodiment, the WDM coatings 118 comprise a first coating 118a, a second coating 118b. and a third coating 118c that are consecutively positioned along the second surface 110. Furthermore, the coatings 118a, 118b and 118c are adapted to transmit a narrow range of wavelengths centered about the wavelengths λi, λ₂, and λ₃ respectively.

The input beam 102 having wavelength components λi, λ and λ₃ is directed toward the input face 120 of the device 100 so as to define an input angle θ with respect to a line normal to the first surface 108. Upon entering the input face portion 120, the input beam 102 is refracted so as to provide a first refracted beam 122 that travels toward the first WDM coating 118a. Upon striking the first WDM coating 118a, the component of the input beam 102 having the wavelength λi is transmitted through the first WDM coating 118a so as to provide a narrow-band first output beam 104a of wavelength λi that defines a first exit angle φi which is substantially equal to the input angle θ.

As shown in Figure 3, the first WDM coating 118a partially reflects the first refracted beam 122 so as to provide a first reflected beam 126 having the wavelength components λ , and λ₃. In particular, the first reflected beam 126 travels through the wall 106 and is reflected by the reflecting region 114 of the first surface 108 so as to provide a second reflected beam

128 having the wavelength components λ₂, and λ₃. The second reflected beam 128 is then directed toward the second WDM coating 118b so as to provide a narrow-band second output beam 104b of wavelength λ that defines an exit angle φ₂ which is substantially equal to the input angle θ.

The second WDM coating 118b partially reflects the second reflected beam 128 so as to provide a third reflected beam 132 having the wavelength component λ₃. In particular, the third reflected beam 132 travels through the sheet 106 and is reflected by the reflecting region 114 of the first surface 108 so as to provide a fourth reflected beam 134 having the wavelength components λ₃. The fourth reflected beam 134 is then directed toward the third

WDM coating 118c so as to provide a narrow-band third output beam 104c of wavelength λ₃ that defines a third exit angle φ₃ which is substantially equal to the input angle θ.

Thus, the WDM coatings 118 enable the input beam 102 to be separated according to wavelength. Furthermore, by providing the filtering regions 116 along the second surface 110 of the sheet 106 and by providing the reflecting region 1 14 along the first surface 108 of the sheet 106, the filtered output beams 104 are directed in a substantially parallel mariner.

Reference will now be made to Figure 4 which illustrates another embodiment of the wavelength filtering beamsplitter device 100 which receives a polychromatic beam 140 of light having a first and second plurality of wavelength components. The device 100 provides a plurality of narrow-band output beams 142 corresponding to the first plurality of wavelength components of the input beam 140 that exit the device 100 in a first direction. The device 100 provides a second plurality of narrow-band output beams 144 corresponding to the second plurality of wavelength components of the input beam 140 that exit the device

100 in a second direction.

In this embodiment, the device 100 comprises the sheet 106 having the first and second parallel surfaces 108, 110. Furthermore, the first surface 108 forms the input face portion 120 adjacent the refracting region 1 12 that is adapted to receive the input beam 140.

Moreover, the plurality of WDM coatings 118 are disposed along the second surface 110 so as to provide the second surface 1 10 with the plurality of wavelength filtering regions 116 and so as to provide the device 100 with the plurality of output face portions 124 adjacent the second surface 1 10 in the manner of Figure 3. However, in this embodiment, the reflecting region 114 of the first surface 108 of the embodiment of Figure 3 is replaced by a second plurality of wavelength filtering regions 146. In particular, a second plurality of WDM coatings 148 are disposed along the first surface 108 so as provide the second wavelength filtering regions 146 and a second plurality of output face portions 150 adjacent the regions 146. Consequently, the second plurality of output beams 144 exit the second output faces 150 along substantially parallel directions. Since the second output faces 150 are disposed along the first surface 108, the second output beams 144 exit the device 100 along a direction which is different from that of the first output beams 142.

Although the preferred embodiment of the present invention has shown, described and pointed out the fundamental novel features of the invention as applied to this embodiment, it will be understood that various omissions, substitutions and changes in the form of the detail of the device illustrated may be made by those skilled in the art without departing from the spirit of the present invention. Consequently, the scope of the invention should not be limited to the foregoing description, but should be defined by the appending claims.

Claims

WHAT IS CLAIMED IS:

1. A beamsplitter device for splitting an input light beam having at least first and second components into corresponding spatially separated first and second substantially parallel output light beams, said device comprising: a transparent member comprising an input face having at least one input face portion and an output face having at least two output face portions, said input face portions oriented to refract said input beam toward the first output face portion, said first output face portion adapted to (a) transmit the first component of the input beam through the first output face portion so as to provide the first output beam and (b) reflect said second component of the input beam; said second output face portion disposed to receive the second component of the input beam, said second output face portion adapted to transmit the second component of the input beam through the second output face portion so as to provide the second output beam, said face portions being oriented such that the first and second output beams are output in substantially parallel directions.

2. The device of Claim 1, wherein said face portions are oriented in parallel planes.

3. The device of Claim 2, further comprising a first coating disposed in a plane that is substantially parallel to the plane of the first output face portion, said first coating transmitting the first component of the input beam, said first coating reflecting the second component of the input beam.

4. The device of Claim 3, wherein the first coating is disposed substantially in the plane of the first output face portion.

5. The device of Claim 2, wherein the transparent member further comprises a reflecting portion disposed in a plane that is substantially parallel to the plane of the input face portion, said reflecting portion reflecting the second component of the input beam toward the second output face portion.

6. The device of Claim 5, wherein the reflecting portion comprises a reflective coating disposed substantially in the plane of the input face portion.

7. The device of Claim 2, further comprising an antireflective coating disposed adjacent the second output face portion, said antireflective coating enhancing transmission of the second component of the input beam through the second output face portion.

8. The device of Claim 7, further comprising a second antireflective coating disposed adjacent the input face portion, said second antireflective coating enhancing transmission of the input beam through the input face portion.

9. The device of Claim 1, wherein the first and second components of the input beam are first and second polarization components, and wherein the first and second output beams are orthogonally polarized with respect to each other.

10. The device of Claim 9, wherein the first output beam is p-polarized and wherein the second output beam is s-polarized.

1 1. The device of Claim 1, wherein the first and second components of the input beam are first and second wavelength components, and wherein the first and second output beams have narrow spectral bandwidths.

12. A polarizing beamsplitter device comprising: a structural member comprising a transparent medium having first and second planar substantially parallel surfaces, said first surface refracting light so that an unpolarized input beam of light entering the first surface is directed toward the second surface, said second surface having an output portion with a material that (a) transmits a first polarization component of the input beam through the output portion so as to provide a first polarized output beam and (b) reflects a second polarization component to a reflecting material on the first surface, said reflecting material reflecting the second polarization component of the input beam for refraction through the second surface so as to provide a second polarized output beam, said first and second polarized output beams traveling in substantially parallel directions.

13. The device of Claim 9, wherein the material of the output portion of the second surface is a polarizing coating disposed substantially adjacent the second surface of the structural member.

14. The device of Claim 10. wherein the reflecting material on the first surface is a reflective coating.

15. The device of Claim 1 1, further comprising first and second antireflective coatings respectively disposed on the first and second surfaces of the structural member, said first antireflective coating enhancing transmission of the input beam through the first surface, said second antireflective coating enhancing transmission of the second polarized output beam.

16. A polarizing beamsplitter device comprising: a structural member comprising first and second planar surfaces disposed in substantially parallel planes and a transparent medium disposed between the first and second surfaces; a polarizing coating disposed along a first portion of the second planar surface, said device adapted so that an unpolarized input beam of light entering a first portion of the first planar surface is directed toward the polarizing coating, said polarizing coating transmitting a first polarization component of the input beam so as to provide a first polarized output beam, said polarizing coating reflecting a second polarization component of the input beam toward a second portion of the first planar surface, said second polarization component reflecting at the second portion of the first planar surface toward a second portion of the second planar surface, said second portion of the second planar surface transmitting the second polarization component of the input beam so as to provide a second polarized output beam that travels in a direction which is substantially parallel to that of the first polarized output beam.

17. The device of Claim 16, further comprising a reflective coating disposed along the second portion of the first planar surface.

18. The device of Claim 17. further comprising a first antireflective coating disposed along the first portion of the first planar surface.

19. The device of Claim 18. further comprising a second antireflective coating disposed along the second portion of the first planar surface.

20. A wavelength filtering beamsplitter device comprising: a structural member comprising a transparent medium having first and second planar substantially parallel surfaces, said first surface refracting light so that an input beam of light having a plurality of wavelength components entering the first surface is directed toward the second surface, said second surface having a first and second output portion, said first output portion having material that (a) transmits a first wavelength component of the input beam through the first output portion so as to provide a first narrow-band output beam and (b) reflects a second wavelength component to a reflecting material on the first surface, said reflecting material reflecting the second wavelength component of the input beam toward the second output portion, said second output portion transmitting the second wavelength component so as to provide a second narrow-band output beam, said first and second narrow-band output beams traveling in substantially parallel directions.

21. The device of Claim 20, wherein the material of the first output portion reflects a third wavelength component to the reflecting material on the first surface, said reflecting material reflecting the third wavelength component toward the second output portion, said second output portion having material that (a) transmits the second wavelength component of the input beam through the second output portion so as to provide the second narrow-band output beam and (b) reflects the third wavelength component to the reflecting material on the first surface, said reflecting material reflecting the third wavelength component for refraction through the second surface so as to provide a third narrow-band output beam, said narrow-band output beams traveling in substantially parallel directions

22. The device of Claim 21 , wherein the material of the output portions comprise a plurality of wavelength division multiplexer coatings.

23. The device of Claim 22 wherein the reflecting material on the first surface comprises a second plurality of wavelength division multiplexer coatings, said second plurality of coatings transmitting a fourth and fifth wavelength component of the input beam so as to provide a fourth and fifth narrow-band outpμt beam that travel in substantially parallel directions.