MXPA06000688A - A housing for mounting modulation components - Google Patents

Abstract

A housing (100) for mounting a wire grid polarizing beamsplitter (122) and a spatial light modulator (30) in alignment with an output optical path comprises a front plate having an opening for admitting incident illumination provided along an illumination axis. A modulator mounting plate (110) is spaced apart from and parallel to the front plate, for mounting the spatial light modulator in the optical output path of the illumination axis. First and second polarizer support plates are spaced apart from each other and extend between the front plate and the modulator mounting plate. The respective facing inner surfaces of the first and second support plates provide coplanar support features for supporting the wire grid polarizing beamsplitter between the inner surfaces. The wire grid polarizing beamsplitter extends between the facing inner surfaces. The surface of the wire grid polarizing beamsplitter is a fixed angle with respect to the surface of the spatial light modulator on the modulator mounting plate. The fixed angle defining an output optical axis along the output optical path.

Description

UM ACCOMMODATION FOR MOUNTING MODULATION COMPONENTS FIELD OF THE INVENTION This invention relates generally to digital imaging apparatuses and more particularly relates to a frame for and method for mounting polarization components and a spatial light modulator LCD reflector. BACKGROUND OF THE INVENTION Small-scale image forming devices such as were originally introduced for business presentation markets, digital color projectors have constantly improved in total image forming capacity and light output capacity, so that Digital film projectors compete with conventional motion film projectors such as those used in theaters however - a number of significant technical loads remain. Unlike conventional film projectors, high quality digital projection systems provide separate color modulation paths for red, green and blue (RGB) image data. The digital color projection apparatus design requires that monochromatic light beams carrying images formed in each of the individual color channels be combined, with appropriate intensity and coincidence, in order to project a complete color image. Referring to Figure 2, a simplified schematic is shown for a digital film projection apparatus 10 as described in the Publication of the US Patent Application. . No. 2003/0133079, incorporated herein by reference. Each color channel (r = Rojof g = Greenf b = Blue) uses similar components to form a modulated light beam. The individual components within each path are labeled with a r, g, or b appended, appropriately. For the description that follows, however, distinctions between color channels are specified only when necessary. A light source 20 provides unmodulated light, which is conditioned by uniformal optics 22 to provide uniform illumination, directed through a lighting relay lens 80 to a dichroic separator 27. The separated dichroic separates the white light into red, green and blue channels. After any of the three color channels, the light goes to a light modulation assembly 38 in which a relay lens 82 directs light through a prepolymer 70 to a polarization beam splitter 24. The light having the desired polarization state is transmitted through the polarization beam splitter 24 and is then modulated by a spatial light modulator 30, which selectively modulates the polarization state of the incident light over a pixel array. . The action of the spatial light modulator 30 forms an image. The modulated light of this image, reflected from the polarization beam splitter 24, is transmitted along an optical axis Or / Og / Ob through an analyzer 72 and is directed to an amplification relay lens 28, through from an optional bending mirror 31, to a dichroic combiner 26, typically a Philips X cube prism, or combination of dichroic surfaces in conventional systems. An optional color-selective polarization filter 60 may also be provided in the modulated light path. The dichroic combiner 26 combines the red, green and blue modulated images of separate optical axes 0r / 0g / 0b to form a multi-color, combined image of a projection lens 32 along a common optical O-axis for projection onto a surface 40 of presentation, such as a projection screen. The liquid crystal (LCD) reflecting device of Figure 1 is a type of spatial light modulator that is widely used in digital projector design. This device accepts polarized light and modulates the polarization of the incident light to provide colored light beam as output. To obtain polarized light, a polarization beam splitter prism, such as a McNeille prism, is typically employed in conjunction with the support of one or more polarization elements, configured as polarizers and analyzers. Because the modulated light must be combined with each of three color channels in order to synthesize a color image, the correct registration of the modulated light is important. When the modulated light is reflected from the surface of the spatial light modulator 30, angular errors in the relative alignment of each LCD surface can cause significant shifts in resolution, providing unsatisfactory image quality. Additional image quality problems, such as loss of contrast, may be the result of imperfect alignment of polarization support components, particularly for the polarization beam splitter 24. In addition, the effects of thermal expansion can cause shifting in the register and degrade the operation of polarization components. Thermal expansion becomes a particular interest with high end projection apparatus, since high brightness is required in these applications. At the same time, compact optical packaging with minimized optical path length between the imaging components and the projection lenses is desirable. These conflicting requirements complicate the design of high brightness projection apparatus. The negative impact of thermal expansion on image registration is well known in the industry. In response to this problem, the U.S. Patent. No. 6,4345,895 (Ma i et al) discourages the use of a mounting base to support the reflective spatial light modulators, polarization beam splitters, and related polarization support components. Significantly, the disclosure of the U.S. Patent. No. 6,3458,895 still teaches away from the use of a mounting base formed of metals or composite materials that have low expansion coefficients. Instead, the approach proposed by the US Patent. No. 6,345,895 assembles the spatial light modulator components directly to the glass prism components used to split beam or combine color, so that the components in the optical path remain in alignment with the thermal expansion. This same kind of total approach is also taught in the Patents of E.U.A. Nos. 6,375,330 (Mihalakis); 6,053,616 (Fujimori et al.); and 6,056,407 (Iinuma et al.). A problem recognized with fixation to prism components is to achieve the initial alignment itself. As an example, the U.S. Patent. No. 6,406,151 (Fujimori) discloses methods for adhesively securing the LCD components to a prism with alignment. While fixing directly to a glass or plastic raw surface may have advantages of minimizing the effects of thermal expansion, there appear to be a number of disadvantages with solutions that use adhesives, thermal dissipation issues of composition for the LCD itself and Make replacement of component and procedure costly and time consuming. Recently as described in the Patent of E.U.A. No. 6,122,103 (Perkins et al.), High quality wire mesh polarizers have been developed for use in the visible spectrum. While glass grid polarizers may not exhibit all of the necessary performance characteristics needed to obtain the high contrast required for digital cinema projection, these devices have a number of advantages. Main among these advantages are the following: (i) Good thermal performance. The wire mesh polarizers do not exhibit the birefringence that is characteristic of glass-based polarization devices, as noted above. (ii) Strength. The wire grid polarizers have been shown to be able to withstand the expected light intensity, temperature, vibration, and other environmental conditions necessary for digital cinema projection. (iii) Good angular response: These devices effectively provide a superior numerical aperture than is available using conventional glass polarization beam splitters, which allows relatively higher levels of light output when compared against conventional devices, (iv) Good color response These devices work well under conditions of different color channels. It should be noted, however, that the response within the blue light channel may not require additional compensation. US Patents. Nos. 6, .234,634 and 6,447,120 (both to Hansen et al) and 6,585,378 (Kurtz et al.), Describe imaging apparatuses using wire grid bias beam splitters. The wire grid bias beam splitter offers advantages over conventional prism-based bias beam splitters, particularly due to its small size and weight. It can be appreciated that there could be advantages for light modulation in a combination using polarizer and glass grid analyzer components. However, as with more conventional beam splitters and polarizers employed in prior art projection apparatuses, the glass grid components themselves are subjected to thermal expansion effects and must be properly aligned with respect to the spatial light modulator within each color channel, with thermal effects taken into consideration. An article in the SID 02 Digest titled "The Mechanical-Optical Properties of the Wire-Grid Type Polarizer in Projection Display System "by GH Ho et al, presents some of the key design considerations for deploying wire grid polarizer components in image forming apparatus using spatial light modulators. Reflective LCDs Observing the problems caused by mechanical restraint and thermal stress in a comparatively low energy projection apparatus, the article by Ho et al., Accentuates the total negative impact of conventional mounting techniques for grid polarization beam splitters. Notably, the disclosure of Ho et al. is directed to an image forming system that uses a reflective LCD spatial light modulator that transmits modulated light through a wire-grid bias beam splitter. The problems inherent in that type of system include astigmatism, which can be corrected using technical as described in the article by Ho et al. Among other problems observed in the article of Ho et al., A surface deformation caused by thermal effects in the wire grid bias beam splitter. It can be seen that the problems for low to intermediate energy projection apparatus, as pointed out in the article by Ho et al., Would be even more pronounced for superior energy projection equipment. Among the key design considerations for mounting a wire grid bias beam splitter the surface of this component is maintained in an accurate orientation of 45 degrees relative to both the surface of the spatial light modulator and the surface of an analyzer. A related problem that must be solved in electronic projection apparatus design is the alignment of the spatial light modulator itself with respect to both the wire grid bias beam splitter and the optical projection path. Maintaining precision alignment without the negative effects of thermal displacement is a key design goal for the high-end electronic projection apparatus.

Unlike the image-forming application of the Ho et al. Configuration, the projection apparatus 10 of Figure 1 (of which the present invention is a part) uses reflector spatial light modulators LCD 30r, 30g, 30b which direct the modulated light back to the corresponding bias beam splitters 24r, 24g, 24h, which in turn reflect light towards the image forming lens. In order to replace the wire grid bias beam splitter with conventional prism-based bias beam splitter components, the thermal effects mentioned by Ho et al. Should be considered. However, because the position of the polarization beam splitter is like a reflective surface in the modulated light path, the thermal impact inherent in imaging problems is even more pronounced than for the system described in Ho's article. and col. That is, with the grid polarization beam splitter components used in place of the polarization beam splitters 24r, 24g. 24b, convergence, contrast, and general wavefront aberrations are serious issues for the optical designer. These optical effects are due to surface deformation, lateral displacements, or tilt and / or rotations, and all of which can be induced by thermal stress. Ho et al., Not only considers the problems encountered with high intensity illumination, but also these specific problems incurred in the reflective structure, and the solutions thereof are not considered by Ho et al. As another recent reference, the Publication of Patent Application of E.U.A. 2003/0117708 (Kane) discloses a sealed enclosure comprising a wire grid bias beam splitter, a spatial light modulator and a projection lens having the interior space filled with an inert or void gas. Among the goals manifested in E.U.A. 200370117708 protection of the corrosion wire grid component and handling and modular packaging of the optical assembly are found. While this approach may be useful in some small scale projection environments employing only a single spatial light modulator, the apparatus and method of E.U.A. 2003/0117708 would not be appropriate for the high heat environment of a full color projection apparatus designed for commercial use, such as for use in movie theaters. In addition, high quality digital projection requires the use of separate spatial light modulator for each color channel, with high quality projection optics. In order to provide appropriate contrast, additional support components for the polarization beam splitter are needed to provide additional polarization selectivity. The relative alignment of these support polarization components with the polarization beam splitter and with the total image formation path is significant. No provision is made to deploy or add these support components in E.U.A. 2003/0117708. In addition, the methods of E.U.A. 2003/0117708 do not anticipate and proportions solutions due to thermal distortion and stress birefringence that would be induced in a high heat environment, as a result of over restriction and heat containment within the sealed envelope. In this way it can be seen that, while wire grid polarizers and polarization beam splitters offer some advantages for digital projection apparatus, the problems of alignment and complexities presented by thermal expansion effects must be resolved in order to obtain proper functioning of these components. SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus and technique for mounting the spatial light modulator and support polarization components that is mechanically strong, which permits thermal expansion without degrading the image quality, and which allows alignment direct of components in the path of light modulation. With this object in mind, the present invention provides a housing for mounting a wire grid bias beam splitter and a spatial light modulator in alignment with an optical output path, comprising: (a) a face plate having an opening to admit incident lighting provided along a lighting axis; (b) a modulator mounting silver, spaced apart from and parallel to the faceplate, for mounting the spatial light modulator in the path of the illumination axis; (c) first and second polarizer support plates, spaced apart from one another and extending between the front plate and the modulator mounting plate; the respective oriented internal surfaces of the first and second support plates providing coplanar support features to support the wire grid bias beam splitter between the internal surfaces; and the wire grid bias beam splitter being extended between and normal to the inner facing surfaces, the surface of the wire grid bias beam splitter at a fixed angle with respect to the surface of the spatial light modulator in Modular mounting plate, fixed angle defining an output optical axis along the optical output path. It is a feature of the present invention that provides a modular housing for a spatial light modulator and support polarization components for a single color channel. An advantage of the present invention is that it provides a mounting method for accurately aligning the wire grid bias beam splitter relative to the optical path of modulated light. Using the apparatus and method of the present invention it is not necessary to adjust the position of the polarization beam splitter once the housing is mounted in place. Only light adjustment of the placement of the spatial light modulator is necessary for any color channel. It is a further advantage of the apparatus and method of the present invention that allows for conventional optical manufacturing tolerances that are used in the manufacture of a precision alignment housing. A further advantage of the present invention is that it allows the replacement of the spatial light modulator for a single color channel without requiring the readjustment of the support polarization components. The complete set of modulation and polarization components for a single color channel are packaged as a unit, allowing ease of removal for serviceability. Still a further advantage of the present invention is that it provides a mounting arrangement for biasing components that is strong and allows for thermal expansion effects. These and other objects, features and advantages of the present invention will become apparent to those skilled in the art upon reading the following detailed description when taken in conjunction with the drawings, wherein an illustrative embodiment of the invention is shown and described. invention. BRIEF DESCRIPTION OF THE DRAWINGS. While the specification concludes with claims that notably and distinctly claim the subject matter of the present invention, it is believed that the invention will be better understood from the following description when taken in conjunction with the accompanying drawings, in where: Figure 1 is a schematic block diagram showing the total arrangement of components for a projection apparatus using a reflector LCD spatial light modulator; Figure 2 is a perspective view showing components of the housing of the present invention, in relation to other components in the optical path; Figure 3 is a perspective view showing the components of the housing of the present invention amplified, without mounting details shown in Figure 2; Figure 4 is a perspective view showing internal components of the housing of the present invention, with the analyzer removed; Figure 5 is a perspective view showing the internal components of the housing of the present invention for modulation and polarization, with the top cover plate removed; Figure 6 is a perspective view showing internal components of the housing of the present invention, with the top cover plate removed and with representative light cones shown for illumination and modulated light; and Figure 7 is a detailed perspective view showing the key support structure separated from the mounting plate used for fixing the spatial light modulator. DETAILED DESCRIPTION OF THE INVENTION The present description is directed in particular to elements that are part of, or cooperate more directly with, the apparatus according to the invention. It should be understood that elements not specifically shown or described can take various forms well known to those skilled in the art. Referring to Figures 2 and 3, perspective views of a housing 100 for mounting the spatial light modulator 30 and its support biasing components for a single color modulation channel, the blue channel in a preferred embodiment, are shown. , to a chassis wall 104 within the projection apparatus 10. The monochromatic illumination 1 is directed to the turning mirror 31 which reflects the illumination 1 through the amplification relay lens 82 and through the ring bore 102 towards the housing 100. The modulated output light along the axis Ob is it then directs through the reduction relay lens 28 for combination and projection optics, as described with reference to Figure 1. A modulator assembly 106 is fixed as part of the housing 100. Referring to Figure 4, it is shown a front perspective view with the analyzer 72 removed to show the internal components and the overall structure of the housing 100. The modulator assembly 106 is fixed to a modulator mounting plate 110. Adjusted on the modulator mounting plate 110 are an upper plate 112 and a base plate 120, separating the modulator mounting plate 110 and the ring bore 102. Within the housing 100, a wire grid bias beam splitter 122 is disposed at a fixed diagonal angle relative to the surface of the spatial light modulator 30. A register recess 118 is provided along the edge of the base plate 120, providing a seat for the lower edge of the analyzer 72. The pre-polarizer 70 is mounted within a recess 108 provided by the ring bore 102 and is slightly fixed in position using a flexible adhesive, such as an RTV type adhesive. Referring to Figure 7, a perspective view of housing 100 is shown with the modulator mounting plate 110 removed. The housing portion 100 consisting of the upper plate 112, the base plate 120 and the ring bore 102 can be manufactured as a single unit, such as by casting. In any manner in which the housing 100 is manufactured, the corresponding support features on the orientation surfaces of the base plate 120 and the top plate 112 must be mutually aligned so as to coincide with the grid bias beam splitter 122. of wire and the analyzer 71 between these surfaces with minimal restriction. The wire grid bias beam splitter 122 is adjusted against the coplanar recording surfaces 124 and 1247 on the base plate 120 and the top plate 112, respectively. The lower edge of the wire grid bias beam splitter 122 sits on a beam splitter settlement base 128. In one embodiment, the coplanar recording surfaces 124 and 124 'are aligned to be co-planar coincident, after the assembly of the upper plate 112 and the base plate 120 to the ring bore 102. The edge guides 126 and 126 'are also machined in the same operation to be collinear with the edge of the polarization beam splitter 122 when it is in the housing 100. Similarly, to support the analyzer 72, a register recess 118 in the base plate 120 is aligned so that its back surface is coplanar with the side surface 116 of the top plate 112. The slots 114 are provided in the upper and base plates 112 and 120 by maximizing the flow 109 of air, ambient or dedicated forced air, through one or both surfaces of the polarization beam splitter, also providing additional cooling to the adjacent polarization and modulation components. In addition, the cooling of the polarization beam splitter may have added benefit to prevent differential thermal expansion of the polarization beam splitter and / or its assembly, which could cause the polarization beam splitter to rotate from its normal position and from this induces a convergence error (screen position). The base plate 120 and the top plate 112 can be adjusted towards the modulator mounting plate 110 and the ring bore 102 using conventional matching methods for machined or molded metal components. The pins and detents can be used for alignment of these components to form the outer shell of the housing 100 as shown in FIG. 4. The components are then screwed together to provide a housing 100 as a single modular component. For uniform thermal expansion, similar materials are used for fabrication of the base plate 120, the top plate 12, the modulator mounting plate 110 and the ring bore 102. In a preferred embodiment, the base plate 120, the top plate 112, the modulator mounting plate 110, and the ring hole 102 are made of aluminum. Alternatively, some other material having a low coefficient of thermal expansion can be used, such as Invar or some types of stainless steel for example. The precision alignment with the lighting system (axis 1 as shown in Figures 2 and 3) is not critical; there is some allowable tolerance for alignment in the unmodulated light path. Advantageously, the housing 100 provides self-centering to the lighting axis 1, within allowable tolerance, so that additional manual alignment is unnecessary. Referring again to Figure 3, the barrel of relay lenses 82 provides this self-centering by adjusting to the ring bore 102, which attaches itself to the chassis wall 104. Alignment of Polarization Components Referring to Figure 5, a perspective view of polarization and modulation components is shown, with the top plate 112 and the ring bore 102 removed and with the analyzer 72 shown in place. Figure 5 shows details of the configuration of the modulator mounting plate 110 and the base plate 120. As noted with respect to Figure 7, the base plate 120 has coplanar registration surface 124, or an equivalent time of mechanical particularity that acts as a data to seat the wire grid bias beam splitter 122, in the necessary fixed angle with respect to the spatial light modulator 30. In a preferred embodiment, this fixed angle is at 45 degrees. The beam splitter settlement base 128, shown more clearly in Figure 7, then provides a vertical datum for alignment of the wire grid bias beam splitter 122 in the direction and as indicated in Figure 5. The surface Coplanar register 124 provides a reference for alignment of the wire grid bias splitter 122 in the z direction. An edge guide 126 on the base plate 120 serves as a reference point for horizontal alignment of the wire grid bias beam splitter 122 along the coplanar register surface 124, i.e. in the x direction as is indicated in Figure 5. As shown in Figure 7, a corresponding edge guide 126 'on the top plate 112 is aligned with the edge guide 126 on the base plate 120 to provide a pair of reference points for horizontal alignment (direction x) of an edge of the bias beam splitter 122 extending between the base plate 120 and the top plate 112. In the design of the housing 100, the thermal expansion of the polarization components is allowed in controlled directions, reference points or opposite surfaces. The use of the edge guide 126 and the coplanar registration surface 124 allows the thermal expansion of the wire grid bias beam splitter 122 outwardly from the corner contact point near the edge guide 126. A surface of the wire grid bias beam splitter 122 near its bottom edge is seated against the coplanar register surface 124 on the base plate 120; the upper edge of the wire grid bias beam splitter 122 is against the surface of the coplanar register surface 124 'on the top plate 112, with space provided for thermal expansion along this top edge. A small amount of elastic, flexible adhesive, such as an RTV tape adhesive, can be used to stabilize the lower edge of the wire grid bias beam splitter 122 against the seating base 128 and to stabilize the upper edge of the splitter 122 of wire-mesh polarization beam to the surface of the coplanar register surface 124 'on the top plate 112. Similarly, in analyzer 72, seated against register recess 118 as shown in Figure 7, it can expand at its upper edge, which is flexibly adhered to side surface 116. Allowing some tolerance for thermal expansion and allowing expansion only in predictable directions (x and y as shown in Figure 5), the design of the housing 100 minimizes bending or other distortion of the bias beam splitter 122 to the minimum in this manner. wire grid and analyzer 72 due to thermal effects. It can be seen that the fabrication of the housing 100 as shown in Figures 4, 5 and 7 allows the approximate, initial placement of polarization and modulation components relative to the projection optics for a color channel, i.e., providing initial alignment of the three polarization components (prepolarizer 70, beam splitter 122). wire grid polarization, and analyzer 72), and spatial light modulator 30. There remains, of course, some small tolerance related to the alignment of the edges of the wire grid polarization components with the precise polarization axis of these components, accurate to within about 0.5 degrees using current manufacturing techniques. The optical tolerances and conventional machining practices can be used in the manufacture of the housing 100. Advantageously, the housing 100 allows the three polymerization components to be assembled with the necessary precision, not requiring additional adjustment once these components are adjusted in their place. The housing 100 can then be mounted against the chassis wall 104. The precision alignment of the optical output path (for example, the Ob in FIGS. 3 or 5) is then obtained by adjusting the relative position of the spatial light modulator 30 in the modulator mounting plate 110. This final precision alignment is a minor adjustment, typically in the order of a few microns, and can be done once the projection apparatus assembly 10 is complete. To provide image registration with the necessary precision, the following alignments are of particular importance: (i) alignment of the wire grid bias beam splitter 122 to the output optical axis, 0b as shown in Figure 5; (ii) aligning the wire grid bias beam splitter 122 with respect to the spatial light modulator 30; and (iii) aligning the analyzer 72 to the wire grid bias beam splitter 122 and the output optical axis, Ob. Thus, with the apparatus and method of the present invention, the alignments (i) and (iii) above are achieved by assembling the components within the housing 100 and mounting the housing 100 to the chassis wall 104, as shown in FIG. Figure 2. The alignment (ii) above requires that the spatial light modulator 30 be placed against the modulator mounting plate 110 and snapped into place. With this arrangement, then, only an in situ adjustment, that of the spatial light modulator 30, is needed for optical alignment of the components of the light modulation assembly 38 within each color channel. Figure 6 shows a perspective view showing the light cones transmitted through and reflected from the wire grid bias beam splitter 122. The alignment of the pre-polarizer 70 for the lighting path 1, provided by its assembly within the ring bore 102, is sufficiently within the tolerance when the housing 100 is completely assembled. Alignment of Spatial Light Modulator 30 Referring again to Figure 1, the alignment problem for the spatial light modulator 30 can be appreciated more easily. Each color channel Or / Og / Ob must be aligned with respect to the dichroic combiner 26 in order to accurately align with the optical output O axis. Using the housing 100, the position of each spatial light modulator 30 when initially mounted to the modulator mounting plate 110 will already be within some reasonable alignment tolerance, typically within a few pixels, for example. The slight adjustment of position of each spatial light modulator 30, using a projected image target, such as would be familiar to those skilled in the field of optical alignment, then follows the final alignment within the projection apparatus 10. When this alignment is achieved, each spatial light modulator 30 can be traced in place, using adhesives and techniques well known in the opto-mechanical field. A secondary design consideration with the location of the housing 100 is related to minimizing the escape of light that could reduce the image contrast. Referring to Figure 5, some diffuse light S of the illumination path 1 can be reflected from the surface of the wire grid bias beam splitter 122 instead of being completely transmitted to the spatial light modulator 30. Any type of reflective surface in the path of this reflected, unwanted, diffuse light S could reflect some portion of this light through the wire grid bias beam splitter 122 in the direction of the output axis Ob, thereby reducing the contrast. In this way, the use of non-reflective materials within the possible diffusion path, the reflected S light is recommended. In one embodiment, light absorbing materials are provided in the diffuse S light path. The designations "upper" and "lower" refer to the arrangement of the housing 100 and its components in one embodiment, the angular orientation of the housing 100 could be varied within the scope of the present invention.The coplanar reference surfaces for alignment could be provided by an arrangement of appropriately placed mounting points provided in the upper and base plates 112 and 120, such as using pins or other locating features.The analyzer 72 and pre-biaser components 70 themselves could be grid-biased components wire and could be other types of conventional flat polarization devices The analyzer 72 could be a polymer-based polarizer, for example. Unlike conventional mounting approaches in electronic imaging systems that mount the polarizer components to glass prism components in order to compensate for thermal expansion, the housing 100 of the present invention provides a separate structure that maintains these components in the necessary relation of position one with respect to the other. When the Patent of E.U.A. No. 6,345,895 discourages supporting modulation and polarization components in a metal base, the present invention provides the housing 100 which employs the base plate 120 as a primary support structure for these components. Unlike solutions of the previous branch that require numerous arrangements and adjustments to obtain the necessary alignment for polarization components with each other and with the spatial light modulator, the housing 100 of the present invention maintains the position of these components so that only a minor adjustment of spatial light modulator 30 is needed to align the modulation and polarization components of a color channel with color combination optics.

At the same time, the design of the housing 100 provides this precise alignment of using manufacturing and machining techniques employing only optical tolerances 'conventional. Unlike the apparatus that fixes the components to a combination prism, the housing 100 of the present invention allows each color channel to be assembled, adjusted and serviced independently, minimizing the impact of adjustments in a single color channel on the projection apparatus 10 as an integer. Unlike solutions of the above branch comprising multiple sheet metal components, the housing 100 of the present invention provides a single strong frame for mounting the polarization and modulation components, suitable for a high energy projection system. In this way, what is provided is an apparatus and method for mounting polarization components and a reflector LCD spatial light modulator in a configuration that is thermally strong and allows direct alignment techniques. LIST OF PARTS 10 Projection apparatus 20 Light source 22 Uniformity optics 24 Polarization beam splitter 24r Polarization beam splitter, red 24g Polarization beam splitter, green 24b Polarization beam splitter, blue 26 Dichroic combiner 27 Separator dichroic 28 Amplification relay lens 28r Amplification relay lens, red 28b Amplification relay lens, green 28b amplification relay lens, blue 30 Spatial light modulator 30r Spatial light modulator, red 30g Spatial light modulator, green 30b Spatial light modulator, blue 31 Bending mirror 32 Projection lens 38 Light modulation set 38r Light modulation set, red 38g Light modulation set, green 38g Light modulation set, blue 40 Presentation surface 60 Color-sensitive polarization filter 60r Color-sensitive polarization filter, red 60g Color sensitive polarization filter, green 60b Color-sensitive polarization filter, blue 70 Pre-polarizer 72 Analyzer 80 Lighting relay lens 82 Relay lens 100 Housing 102 Ring bore 104 Chassis wall 106 Modulator mounting 108 Recess 109 Air flow 110 Modulator mounting plate 112 Top plate 114 Slots 116 Side surface 118 Registration recess 120 Base plate 122 Wire mesh bias beam splitter 124 Coplanar recording surfaces 124 '"Coplanar recording surfaces 126 Edge guides 126' Edge guides 128 Settling base of beam splitter.-

Claims (26)

1. CLAIMS 1. A housing for mounting a glass grid bias beam splitter and a spatial light modulator in alignment with an optical output path, comprising: (a) a face plate having an opening for admitting incident illumination provided along a lighting axis; (b) a modulator mounting plate, spaced from and parallel to the faceplate, for mounting the spatial light modulator in the optical output path of the illumination axis; (c) first and second polarizer support plates, spaced apart from one another and extending between the front plate and the modulator mounting plate; the respective internal orientation surfaces of the first and second support plates providing coplanar support features to support the wire grid bias beam splitter between the internal surfaces; and the wire grid bias beam splitter being extended between and normal to the inner facing surfaces, the surface of the wire grid bias beam splitter at a fixed angle with respect to the surface of the spatial light modulator in the modulator mounting plate, the fixed angle defining an output optical axis along the optical-output path.
2. 2. A housing according to claim 1, wherein the first and second polarizer support plates further provide a pair of first and second coplanar edge support members to coincide one edge of the grid polarization beam splitter. wire.
3. 3. A housing according to claim 1, wherein the first polarizer support plate further comprises a first analyzer settlement feature for supporting a surface of an analyzer and aligning an edge of the analyzer; the first particularity of coplanar analyzer seat with a second corresponding analyzer seat particularity in the second polarizer support plate; and the first and second polarizer support plates thereby providing support for an analyzer extended between the first and second polarizer support plates in the optical output path.
4. 4. A housing according to claim 1, wherein the support plates provide adequate ventilation for ambient or forced air flow through the polarization and modulation components.
5. 5. A housing according to claim 1, wherein the spatial light modulator is a reflector liquid crystal spatial light modulator.
6. 6. A housing according to claim 1, wherein the faceplate further comprises a recess for receiving a pre-polarizer.
7. 7. A housing according to claim 1, wherein the opening in the faceplate is a ring bore.
8. 8. A housing according to claim 1, wherein the fixed angle of the surface of the wire grid bias beam splitter with respect to the surface of the light modulator spaced on the modulator mounting plate is a diagonal .
9. 9. A housing according to claim 1, wherein the c.oplanar support features are selected from the group consisting of machined and passed locating surfaces
10. 10. An accommodation according to claim 3, wherein the The analyzer comprises a wire grid biasing component.
11. 11. A housing according to claim 3, wherein the analyzer comprises a polymer-based polarizer.
12. 12. A housing for mounting a wire grid bias beam splitter and a spatial light modulator in alignment with an optical output path, comprising: (a) a face plate having an opening for admitting incident illumination provided along a lighting axis through a prepolymer component; (b) a modulator mounting plate, spaced from and parallel to the faceplate, for mounting the spatial light modulator in the path of the illumination axis; (c) first and second polarizer support plates, spaced apart from one another and extending between the front plate and the modulator mounting plate; the respective oriented internal surfaces of the first and second support plates providing coplanar support features to support the wire mesh bias beam splitter extended between the internal surfaces; wherein the first and second polarizer support plates provide a pair of first and second coplanar edge support members for registering an edge of the wire grid bias beam splitter; the first and second polarizer support plates further comprising coplanar support features for mounting an analyzer in the output optical path; and the wire grid bias beam splitter being extended between and normal to the inner facing surfaces, the surface of the wire grid bias beam splitter at a fixed angle with respect to the surface of the spatial light modulator in the modulator mounting plate, the fixed angle defining an output optical axis along the optical output path.
13. 13. A housing according to claim 12, wherein the spatial light modulator is a reflector liquid crystal spatial light modulator.
14. 14. A housing according to claim 12, wherein the opening in the front plate is a ring bore.
15. 15. A housing according to claim 12 wherein the fixed angle of the surface of the wire grid bias beam splitter with respect to the surface of the spatial light modulator in the modulator mounting plate is a diagonal.
16. 16. A housing according to claim 12 wherein the coplanar support features are selected from the group consisting of machined surfaces and locating pins.
17. 17. A housing according to claim 12, wherein the analyzer comprises a wire grid biasing component.
18. 18. A housing according to claim 12 wherein the prarizer component comprises a wire grid biasing component.
19. 19. A housing according to claim 12 wherein the prarizer component comprises a polymer based polarizer.
20. 20. A housing for mounting a wire grid bias beam splitter and a spatial light modulator and alignment with an optical output path, comprising: (a) a face plate having an opening for admitting incident illumination provided along a lighting axis; (b) a modulator mounting means for mounting the spatial light modulator in the path of the illumination axis; (c) first and second polarizer support plates, spaced apart from each other and extending from the faceplate; the respective oriented internal surfaces of the first and second support plates providing coplanar support features to support the wire grid bias beam splitter between the internal surfaces; and the wire grid bias beam splitter being extended between and normal to the internal oriented surfaces, the surface of the wire grid bias divider at a fixed angle with respect to the surface of the spatial light modulator, the fixed angle defining, by reflection of lux from the spatial light modulator, an optical output axis along the optical output path.
21. 21. A method for mounting a wire grid bias beam splitter and a spatial light modulator in alignment with an optical output path, comprising: (a) directing incident illumination along an illumination ej; (b) mounting the spatial light modulator in the path of the illumination axis (c) extending the wire grid bias beam splitter between the first and second separated polarizer support plates, wherein (i) the internal surfaces The respective orientations of the first and second support plates provide coplanar support features to support the extended wire mesh bias beam splitter between the oriented internal surfaces, (ii) The inner surface of the first polarizer support plate defines a first edge reference for registering a first edge of the wire grid bias beam splitter and defining a first point o a second edge reference for registering a second edge of the wire grid bias beam splitter, wherein the second edge is adjacent and perpendicular to the first edge, the second edge extending between the first and second nda polarizer support plates; (i) the internal surface of the second polarizer support plate defines a second point of the second edge reference: and the wire grid bias beam splitter thus supported in a normal to the surfaces, the surface of the Wireframe polarization beam splitter at a fixed angle with respect to the surface of the spatial light modulator, the fixed angle defining an output optical axis along the optical path of output.
22. 22. A method for assembly according to claim 21, wherein the step of extending the wire grid bias beam splitter between the first and second polarizer support plates further comprises the step of applying a flexible adhesive on a contact point of the wire grid bias beam splitter against the inner surface of the second polarizer support plate.
23. 23. A method for assembly according to claim 21, further comprising the step of extending an analyzer between coplanar support features in the first and second support plates.
24. 24. A method for assembly according to claim 21, further comprising the step of adjusting the position of the spatial light modulator for alignment of the output optical axis.
25. 25. A method for assembly according to claim 21, wherein the step of mounting the spatial light modulator comprises the step of fixing the spatial light modulator to a mounting plate, the mounting plate being attached to the first and second polarizer support plates,
26. 26. A mounting method according to claim 21, wherein the fixed angle is diagonal. SUMMARY OF THE INVENTION A housing (100) for mounting a wire mesh bias beam splitter (122) and a spatial light modulator (30) in alignment with an optical output path comprises a face plate having an aperture to admit incident illumination provided along a lighting axis. The modulator mounting plate (110) is spaced from and parallel to the faceplate, for mounting the spatial light modulator on the optical output path of the illumination axis. First and second polarizer support plates are spaced from each other and extend between the front plate and the modulator mounting plate. The respective oriented internal surfaces of the first and second support plates provide coplanar support features to support the wire grid bias beam splitter between the internal surfaces. The wire grid bias beam splitter extends between the internal oriented surfaces. The surface of the wire grid bias beam splitter is at a fixed angle with respect to the surface of the spatial light modulator in the modulator mounting plate. The fixed angle defining an optical output axis along the optical output path.