Patent Publication Number: US-9835301-B2

Title: Optical systems and methods for pole luminaires

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 62/019,747 filed Jul. 1, 2014, which is incorporated by reference herein. 
    
    
     BACKGROUND 
     Luminaires for outdoor lighting are often designed for aesthetic appeal of the equipment when it is directly viewed, as well as for providing high quality illumination. Certain pole mounted luminaires position a light emitter such that light emits through an aperture covered by a lens or screen that protects the light emitter, but does not enhance the aesthetics of the aperture as seen by a viewer. Also, the reverse is sometimes true for a pole light, that is, the aperture looks nice but there is very little in the way of a photometric distribution (i.e., the pole luminaire is a rather dimly lit “marker light.”) 
     SUMMARY 
     in an embodiment, a pole luminaire is configured for mounting to a base and for illuminating an area adjacent to the base. The pole luminaire includes a core structure, that in turn includes a plurality of substantially vertical side portions that are configured to couple with and extend vertically from the base. The substantially vertical side portions are disposed about an elongate, open central shaft. The luminaire also includes one or more luminaire subassemblies that couple with the core structure. Each luminaire subassembly includes a housing having a face panel, wherein an aperture is defined in the face panel and comprises a height and a width. A face plate coupled within the aperture. Each luminaire subassembly also includes a light engine including one or more light emitters, wherein light emitted by the one or more light emitters is directed through the aperture and the face plate into the area. 
     In an embodiment, a pole luminaire illuminates an illuminated area, and includes a base, a core structure mounted with and extending vertically from the base, and one or more power supplies within the core structure. A plurality of subassemblies couple with the core structure so as to prevent visibility of the core structure from any side. At least one of the subassemblies is a luminaire subassembly that includes a face panel having a length along the core structure, and defining one or more apertures therein, and a rear panel. Associated with each of the one or more apertures, is a horizontal row of light emitters, a diffuser, a reflector, a face plate and a rear shell. The horizontal row of light emitters is disposed within an interior space between the face panel and the rear panel. The light emitters are disposed adjacent to an inner surface of the face panel along an upper edge of the aperture, and are oriented to emit light toward the interior space. The diffuser is disposed within the interior space such that substantially all of the light from the light emitters impinges on the diffuser and is diffused. The reflector has a shape that is concave with respect to the aperture and the illuminated area, such that the light from the diffuser is reflected toward the aperture. The face plate is coupled within the aperture such that the light passes through the aperture at the face plate after it is reflected by the reflector. The rear shell is coupled with the face panel, and encloses at least the light emitters, the diffuser and the reflector within the interior space. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments are described in detail below with reference to the following figures, in which like numerals within the drawings and mentioned herein represent substantially identical structural elements. 
         FIG. 1  is an isometric view of a pole luminaire, according to an embodiment. 
         FIG. 2  is a schematic cross-section of an optical system for a pole luminaire, according to an embodiment. 
         FIG. 3  is a schematic ray trace diagram showing selected components of the optical system of  FIG. 2 . 
         FIG. 4  is a schematic exploded diagram of selected components of the optical system of  FIG. 2 , and of a housing for a pole luminaire, according to an embodiment. 
         FIG. 5A  is a schematic exploded diagram of components of a portion of a pole luminaire, according to an embodiment. 
         FIG. 5B  illustrates the portion of the pole luminaire of  FIG. 5A , fully assembled. 
         FIGS. 6A and 6B  show exemplary details of the core structure of the pole luminaire of  FIGS. 5A and 5B , and one subassembly thereof, according to an embodiment. 
         FIGS. 7A and 7B  illustrate portions of a luminaire subassembly and a core structure with a connector plug that provides a water resistant connection between the core structure and the luminaire subassembly, according to an embodiment. 
         FIGS. 8A and 8B  schematically illustrate a pole luminaire having two curving outer faces, according to an embodiment. 
         FIG. 9  is a rear view of a portion of a face plate that may couple within an aperture of a pole luminaire, showing vertical ridges therein, according to an embodiment. 
         FIG. 10  is an enlarged, top plan view of a portion of the face plate of  FIG. 9 . 
         FIG. 11  shows a polar plot of photometric distributions for a single aperture of a pole luminaire, according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The subject matter of embodiments of the present invention is described here with specificity to meet statutory requirements, but this description is not intended to limit the scope of the claims. The claimed subject matter may be embodied in other ways, may include different elements or steps, and may be used in conjunction with other existing or future technologies. This description should not be interpreted as implying any particular order or arrangement among or between various steps or elements except when the order of individual steps or arrangement of elements is explicitly described. Each example is provided by way of explanation, and not as a limitation. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a further embodiment. Thus, it is intended that this disclosure includes modifications and variations. 
     Pole luminaires, and optical systems and methods used in such pole luminaires are disclosed according to various embodiments. These luminaires, systems and methods generally provide lighting generated by light emitters, shaped by optics and emitted through apertures in a pole shaped housing. 
       FIG. 1  is an isometric view of a pole luminaire  50 , according to an embodiment. Pole luminaire  50  mounts on a base  60  and presents four sides  70 ; sides  70 - 1  and  70 - 2  are labeled in  FIG. 1 , while two others of the four sides are hidden from view. The number of sides  70  in pole luminaire  50  can vary from as few as two sides to any number of sides; embodiments with two, three and four sides represent especially advantageous choices in terms of balancing lighting coverage against complexity of design and manufacturing, as discussed below. Pole luminaire  50  as illustrated in  FIG. 1  includes an optional base transition  230  that may be considered part of base  60 , but is not included in all embodiments. Base transition  230  and other possible base transitions may advantageously provide visual continuity so that luminaire  50  presents no abrupt cross-sectional change at a transition from a structural support portion to a portion that includes luminaire subassemblies that provide light. For example, in  FIG. 1 , base transition  230  provides a substantially similar or identical cross-section to the portion of pole luminaire  50  at the location marked C, from which subassemblies  210  continue upward. In luminaire  50 , a core structure (hidden in the view of  FIG. 1 ) couples to base  60  through base transition  230 , and includes two or more substantially vertical side portions that couple with base  60  (through base transition  230 ) and are arranged about an elongate, open central shaft  221 . One or more luminaire subassemblies  210  couple with the core structure (see  FIGS. 5A, 6A, 6B, 7A, 7B ). In embodiments, subassemblies  210  couple with the core structure and are disposed adjacent to one another so as to prevent visibility of and/or access to the core structure from any side, as also described further below. 
       FIG. 5A  is a schematic exploded diagram of components of portions of a pole luminaire  200 , according to an embodiment.  FIG. 5B  illustrates the portion of pole luminaire  200  that is shown in exploded form in  FIG. 5A , fully assembled.  FIG. 5A  schematically illustrates five luminaire subassemblies  210  with a core structure  220  that includes vertical side portions  222 , as shown. Three of the luminaire subassemblies are designated as  210 - 1 ; one instance each of luminaire subassemblies  210 - 2  and  210 - 3  are also present. As shown in  FIG. 5A , core structure  220  may couple with, and extend vertically from a base (not shown), via a base transition  230 . (As noted above, in other embodiments, core structure  220  may couple directly with a base, such as base  60 ,  FIG. 1 ). Core structure  220  may for example provide a convenient and protected location in which to locate power supplies, driver circuitry, wiring and the like for subassemblies  210 . Each subassembly  210  includes a housing  201  formed by a face panel  120  having apertures  125  therein, and a rear shell  214  that includes a rear panel.  121  and sides  212 . Subassemblies  210  enclose one or more of-light engines  100  ( FIGS. 2-3 ) that project light through the apertures  125  (only a few apertures  125  are labeled in  FIG. 5A ). 
       FIG. 2  is a schematic cross-section of a portion of a luminaire subassembly  210  for a pole luminaire, and illustrating a light engine  100  therein, according to an embodiment. Subassembly  210  illuminates an adjacent illuminated area  10  with at least one light engine  100  housed within the subassembly  210 . Face panel  120  and rear panel  121  of luminaire subassembly  210  define an interior space  15 . Face panel  120  forms one or more apertures  125  that connect between interior space  15  and illuminated area  10 . Aperture  125  has a width (pot shown in the view of  FIG. 2 , see  FIG. 4 ) and a height  127 ; in certain embodiments the horizontal extent is larger than the vertical extent, but this is not required. Any number of apertures  125  may be provided along the height of the subassembly  210 . 
     At least one light engine  100  is provided within the subassembly  210  to emit light through the aperture(s)  125 . Typically, a separate light engine  100  will be provided for each aperture  125  of the subassembly  210 , but that may not always be the case. Rather, the subassembly  210  may include apertures through which no light is emitted, or light from one light engine  100  may be directed through multiple apertures  125 . 
     Light engine  100  includes at least one row of light emitters  110  that may be, for example, discrete light emitting diodes (LEDs) or “chip on board” type light emitters. The embodiment shown in  FIG. 2  has two horizontal rows of light emitters  110  coupled with a PCB  105 , but more or fewer rows of light emitters, and different orientations of rows or staggered arrangements (e.g., zigzags) thereof may be present in embodiments. Light from light emitters  110  is initially directed within housing  201  toward rear panel  121 , and in embodiments is diffused by a diffuser  130 . In embodiments, diffuser  130  may include a phosphor. The light exits into an optical chamber  140  bounded by a reflector  150  and a face plate  160  positioned within aperture  125 . Reflector  150  redirects the light toward face plate  160  (see also  FIG. 3 ) such that the light emits through aperture  125  and face plate  160 . In embodiments, face plate  160  may be a flat, translucent or transparent plate; in other embodiments, face plate  160  is a refractive optical element that further redirects the light as it exits light engine  100  into illuminated area  10 . Although face plate  160  may not be perfectly transparent (e.g., it may introduce some incidental scatter) high transparency of face plate  160  is advantageous so that output direction of light directed thereto can be controlled. 
     The configuration of light emitters  110  within light engine  100  confers certain advantages for a pole luminaire. By forcing all of the emitted light through diffuser  130 , through one or more reflections off of reflector  150  and optionally through refractions and/or reflections within face plate  160 , the emitted light is mixed such that a viewer never perceives the light emitters themselves as individual point sources, but rather perceives the aperture as having a uniform brightness across its length and width. Also, given that reflections and optical path length are advantageous in terms of mixing the light, orienting light emitters  110  so that they emit rearwardly allows “folding” of the optical path such that depth of light engine  100  is minimized, leaving room within the pole luminaire for a core structure (described below) to provide structural support and passages for electrical wiring, driver circuits and the like. Furthermore, the rearwardly-emitting orientation of light emitters  110  allows PCB  105  to mount in thermal communication with face panel  120  so that heat generated by light emitters  110  has a very short external heat dissipation path through face panel  120 . 
       FIG. 3  is a schematic ray trace diagram showing selected components of light engine  100 ,  FIG. 2 . Rays  80  of  FIG. 3  are traced backwards, that is,  FIG. 3  shows that rays entering face plate  160  along the upward paths shown, will reflect one or more times from reflector  150  and arrive at diffuser  130 . The reason for backwards ray tracing is to determine what an observer at a given angle will perceive when looking at aperture  125  ( FIG. 2 ) or one or more points thereof.  FIG. 3  shows that light engine  100  will provide a uniform perception of luminance from bottom to top of aperture  125  to an observer who looks at aperture  125  from the angle shown, not a combination of some luminance and a view of (non-illuminated) components within light engine  100 , or a reflected view of objects outside light engine  100 . The combined shaping of reflector  150  and faceplate  160  provide this same treatment of backwards rays, and therefore visual experience, within an angular zone ranging from about 20 degrees to about 90 degrees below horizontal. Conversely, the shaping of reflector  150  and faceplate  160  are also such that backwards rays coming from a zone about 10 degrees below horizontal to anywhere above horizontal—an angular zone being associated with higher potential for glare, light trespass and light pollution—do not trace back to diffuser  130  and/or light emitters  110 . While some light is still emitted by the optical system in this zone (see  FIG. 11 ) this is solely due to scatter from optical imperfections, internal Fresnel reflections and the like that represent a far smaller proportion of light output than that which is directed downwardly. Reflector  150  typically spans aperture  125  in both the horizontal and vertical directions. Curvature of reflector  150  may vary from that shown, but will generally be concave with respect to aperture  125  and illuminated area  10 . Also, advantageously, the curve of reflector  150  will be continuous across the height of aperture  125 , such that visually distracting lines that would be formed by angles in the reflector are avoided in the illumination projected into illuminated area  10  (and thus are avoided in the appearance of aperture  125  as viewed from illuminated area  10 ). 
       FIG. 4  is a schematic exploded diagram of selected components of light engine  100 ,  FIG. 2 , as well as face panel  120  and an inner housing shell  124  that encloses light engine  100  against face panel  120 , according to an embodiment. In  FIG. 4 , both a width  126  and a height  127  of one aperture  125  are shown. Aperture  125  is shown in  FIG. 4  with relatively square or sharp corners, but other embodiments may feature rounded corners. Face panel  120  includes pegs  122  that extend rearwardly from the inner surface of face panel  120  (e.g., toward rear panel  121 , see  FIGS. 2 and 5A ) to provide mechanical support and alignment for portions of light engine  100 . PCB  105  has light emitters  110  coupled thereto; apertures of PCB  105  align with pegs  122  of face panel  120  to align PCB  105  and light emitters  1110  in a known location with respect to face panel  120 . Inner housing shell  124  also features apertures that align with pegs  122  to facilitate positioning, alignment and assembly of light engine  100 , and to improve structural integrity of the assembled luminaire subassembly. Inner housing shell  124  encloses reflector  150  (reflector  150  is hidden in the view of  FIG. 4 ; see  FIGS. 2 and 3 ). An optional gasket  170  is interposed between face plate  160  and an inner surface of face panel  120  about a peripheral edge of aperture  125 , sealing face plate  160  to face panel  120  to protect the elements that are between face plate  160  and inner housing shell  124 . Diffuser  130  and reflector  150  may be retained by being surrounded by face panel  120  and inner housing shell  124 , and/or may be affixed therein using mechanical fasteners or adhesives. The inner surface of face panel  120  may form a groove  129  that receives a gasket, against which a rear shell (e.g., rear shell  214 , see  FIG. 5A ) can seal to face panel  120 . 
     Subassemblies  210  are positioned around and mounted onto core structure  220  so as to enclose core structure  220  so as to prevent visibility of the core structure from any side, providing a neat and sleek appearance to the pole luminaire. For example, sides  212  of rear shell  214  may be angled relative to face panel  120  and rear panel  121  (e.g., at about or less than 45 degrees, or half of each exterior angle, 90 degrees for a four-sided pole) so that two subassemblies  210  may assemble to form a pole luminaire that is square or rectangular in plan view (that is, sides  212  will not interfere with each other at the outside corners when assembled). However, pole luminaires herein are not limited to square or rectangular pole configurations; it will be understood by those skilled in the art that the principles herein may be adapted to pole luminaires having triangular, pentagonal, hexagonal or any other type of polygonal cross-section by tapering rear shells at appropriate half-angles, or less, of corresponding exterior angles. Furthermore, faces of such luminaires may be planar, as shown herein, or may be curved, with the light emitting devices, reflectors, face plates and the like adapted accordingly (see, e.g.,  FIGS. 8A, 8B ). Embodiments herein may be optimized to provide lighting that is strongest in one, two, three or more directions, by providing a corresponding core structure and adding luminaire subassemblies facing the directions where lighting is desired. It might not be desirable to emit light from all sides the pole luminaire. In such situations, non-illuminating subassemblies could be mounted onto the core structure  220  on such sides. Non-illuminating subassemblies are defined herein as subassemblies that do not explicitly illuminate a surrounding area, but may emit light at a low level for purposes such as to provide decorative accents or convey information. Thus, non-illuminating subassemblies may lack light engines like light engine  100 , but may include other white or colored light sources, or lighted displays. When such light sources are present, they may use color or dynamic variation of light output to convey information, such as pedestrian or motor traffic controls, names of streets, paths or aisles, and the like. When such displays are present, they may operate in a similar manner to other known displays, that is, they may display images, graphics, text or any combination thereof; such displayed items may appear static or may appear to move within the display. In some embodiments, non-illuminating subassemblies provide a flat surface without apertures, while in other embodiments non-illuminating subassemblies include features resembling apertures  125  as discussed above, but without light engines  100 , or with different lighted features. 
     In one embodiment, subassemblies  210  attach to core structure  220  by means of a hanger bracket  240  that mates with a receiver bracket  250  (see also  FIGS. 6A, 6B ). Receiver brackets  250  couple with vertical side portions  222  of core structure  220  such that hanger brackets  240  can suspend luminaire and/or non-illuminating subassemblies (discussed above) thereto in vertical orientation. Hanger brackets  240  and receiver brackets  250  are but examples of many kinds of mating brackets that may be used to couple luminaire and/or non-illuminating subassemblies to core structure  220 . Other forms of mating brackets, such as those in which a feature of one of the brackets is inserted within the other bracket and then slid or rotated to fix it into place, may be used. As discussed below, it may be advantageous to use a type of bracket in which gravity assists in keeping the luminaire and/or non-illuminating subassemblies in place during assembly, after which a cap or other mechanical device secures the subassemblies. It may also be advantageous to use brackets like hanger brackets  240  and receiver brackets  250 , in which the brackets and their corresponding subassemblies may be positioned and then fixed in place by a further component (such as cap  260 , discussed below). Although the following discussion will center on the use of hanger brackets  240  and receiver brackets  250 , it should be understood that any other type(s) of mating bracket(s) may be used. 
       FIGS. 6A and 6B  show exemplary details of core structure  220  and one subassembly  210  respectively, according to an embodiment. Core structure  220  features a receiver bracket  250  on each vertical side portion  222  upon which one or more subassemblies  210  are to be mounted; the corresponding subassemblies  210  have hanger brackets  240  that mount with receiver brackets  250 . As shown in  FIGS. 6A and 6B , slots  255  of receiver brackets  250  are defined at a particular spacing, and tabs  245  of hanger brackets  240  are disposed at the same spacing so that when engaged, hanger bracket  240  forms a mechanically robust, two point connection with receiver bracket  250 . In other embodiments, more than two sets of slots and tabs may be present in receiver and hanger brackets. Also, in embodiments, a ramping slope of tabs  245  helps in assembling subassemblies  210  to slots  255  of receiver brackets  250 , such that gravity helps fully engage hanger brackets  240  and subassemblies  210  to receiver bracket  250  and core structure  220 . The geometries shown of hanger brackets  240  and receiver brackets  250  are exemplary only, and variations thereof will be apparent to those skilled in the art. In embodiments, each of core structure  220  and rear panel  121  of subassembly  210  define opposing apertures  211 ,  213  respectively, through which wiring to provide electrical power to light emitters (e.g., light emitters  110 ,  FIG. 4 ) may be routed and into which a connector plug may be pressed, as now discussed. Upon reviewing and understanding  FIGS. 6A and 6B , it will be appreciated that a subassembly  210  using the hanger bracket  240  shown requires the subassembly  210  to be in a slightly elevated position as hanger bracket  240  enters receiver bracket  250 , after which subassembly  210  settles into place assisted by the force of gravity. Referring back to  FIG. 5A , after subassemblies  210  are in place, cap  260  may be used to secure them in place by constraining them from moving upwards as would be required for their removal from core structure  220 . 
     In embodiments, subassemblies  210  may have differing configurations of apertures  125  (including configurations having no apertures  125 ) and corresponding optical assemblies such that a given installation of pole luminaire  200  can include standard versions of optional base transition  230  and core structure  220 , while configurations of luminaire subassemblies  210  may be chosen for the particular needs of the installation. Standard spacings of hanger brackets  240  and receiver brackets  250  allow this flexibility to extend not only to selections for each side of the installation, but also in the vertical sense. For example,  FIG. 5A  illustrates luminaire subassemblies  210 - 1  that extend for a certain length along core structure  220 . Luminaire subassemblies  210 - 1  have corresponding face panels  120 - 1  (only one such face panel  120 - 1  is visible in the view of  FIG. 5A ). Pole luminaire  200  also includes luminaire subassemblies  210 - 2 ,  210 - 3  that have corresponding face panels  120 - 2 ,  120 - 3 . Luminaire subassemblies  210 - 2 ,  210 - 3  are shorter than subassemblies  210 - 1 , but their lengths add to the same length as subassemblies  210 - 1 . In this way, subassemblies  210 - 1 ,  210 - 2  and  210 - 3  may be implemented in vertical arrangement on each face of pole luminaire  200 , such that each vertical side portion  222  of core structure  220  has luminaire subassemblies  210  coupled thereto that cover its height. Similarly, in certain embodiments, a pole luminaire may couple luminaire subassemblies  210  with one or more vertical side portions  222  of core structure  220 , while in other embodiments, only one or more sides of the core structure have luminaire subassemblies coupled thereto, while other sides are provided with non-illuminating subassemblies that cover the core structure to provide a uniform outward appearance. 
     Embodiments herein may provide substantial resistance to water and other weather related damage. Subassemblies  210 , although not completely sealed, may be substantially weather resistant when assembled with optional gasket  170  and a further gasket between face panel  120  and rear shell  214 . Also, as shown in  FIG. 5A , a cap  260  may be installed atop core structure  220  and subassemblies  210  to provide further protection from the elements and to hold subassemblies  210  in place. Another optional gasket may also be provided to provide further weather resistance between cap  260  and core structure  220  and/or luminaire subassemblies  210 . With all such gaskets in place, the main remaining locations where water might enter are apertures provided for electrical wiring in core structure  220  and in rear shell  214 . These locations may be at least partially protected with a resilient connector plug, as discussed below (see  FIGS. 7A, 7B ). 
       FIGS. 7A and 7B  illustrate a luminaire subassembly  210  and core structure  220  with a connector plug  270  that provides a weather-resistant connection between core structure  220  and luminaire subassembly  210 .  FIG. 7A  is an isometric view of one end of subassembly  210  in isolation with connector plug  270 , while  FIG. 7B  is a cutaway view of the end of subassembly  210  mated to an end of core structure  220 , showing connector plug  270  forming a connection between subassembly  210  and core structure  220 . Connector plug  270  may be formed, for example, of rubber, silicone or other resilient material that is pressed into apertures  211 ,  213  (see also  FIGS. 6A, 6B ). Connector plug  270  may be radially symmetric and may have one or more radial grooves  271  therein that are sized such that plug  270  seats with grooves  2711  within round apertures such as apertures  211 ,  213 . An electrical wire  275  extends from a plug  277  on PCB  105  within subassembly  210 , through an aperture  272  defined by connector plug  270 , and into core structure  220 . Further connections of electrical wire  275  are not shown, but wire  275  may for example terminate in a connector that mates with a corresponding connector in core structure  220 . Alternatively, wire  275  may terminate in a bare wire end suitable for connecting with other bare wire ends using twist-on type connectors, or for plugging into a “poke-in” type connector of an electronic driver module. Although electrical wire  275  is shown originating within subassembly  210  and extending through connector plug  270  into core structure  220 , it is contemplated that a wire may similarly originate within base  60  ( FIG. 1 ), pass through optional base transition  230 , and pass through central shaft  221  of core structure  220  ( FIG. 5A ), then through connector plug  270 , and form a connection to other wires within subassembly  210 . Also, there is no limitation on the type of wire represented by electrical wire  275 ; for example, wire  275  may be a pair or other multiple set of wires to supply power, ground or other voltages, currents or signals to subassembly  210 . 
       FIGS. 8A and 8B  schematically illustrate a pole luminaire  350  having two curving outer faces.  FIG. 8A  is a cross-sectional view taken along a horizontal plane along line  8 A- 8 A in  FIG. 8B , while  FIG. 8B  is an isometric view of an upper portion of luminaire  350 .  FIG. 8A  illustrates a core structure  320  that includes two substantially vertical side portions  322  arranged about an open central shaft  321 . Luminaire subassemblies  310  couple with side portions  322  using mating brackets  340 , which may include hanging and receiver brackets (similar to brackets  240 ,  250 ,  FIGS. 5A, 6A, 6B ) or any other form of mating brackets for coupling one structural member to another. Advantageously, mating brackets  340  are configured such that once wiring is in place, luminaire subassemblies  310  can couple with core structure  320  such that luminaire subassemblies  310  prevent visibility of core structure  320  from any side. Stated another way, in a cross-sectional plan view of pole luminaire  350 , taken at any height above the base or base transition, core structure  320  is completely surrounded by one or more subassemblies, such as shown in  FIG. 8A . At least one subassembly is a luminaire subassembly, but one or more non-illuminating subassemblies could be among those completely surrounding core structure  320 .  FIG. 8B  shows apertures  325  defined by luminaire subassemblies  310 . The principles discussed above, in which light emitters couple to a face panel of luminaire subassemblies  310 , emit light toward core structure  320  and in which the light is diffused and reflected through apertures  325 , can be adapted to provide suitable optical assemblies for luminaire  350 . A cap  360  provides a finished look and provides weather resistance for components within core structure  320 . 
       FIGS. 9 and 10  schematically illustrate certain features of face plate  160  ( FIGS. 2, 3 and 4 ).  FIG. 9  is a rear view of a portion of face plate  160 , showing vertical ridges  410 . Ridges  410  advantageously run vertically on the rear surface of face plate  160  such that light from light emitters, diffusers and/or a reflector of light engine  100  (see  FIGS. 2, 3 and 4 ) is refracted and/or reflected in horizontal directions but not as much in vertical directions. This leads to several advantages. First, light from individual light emitters is blended such that a viewer does not see distracting images within apertures  125 . To accomplish this blending, ridges  410  are advantageously provided at a fairly high multiple of the number of light emitters that occur along a horizontal row. For example, one particular embodiment provides two rows of eight light emitters (light emitters  110 ,  FIG. 4 ) and fifty-six ridges  410  across face plate  160 —a ratio of seven ridges  410  to each light emitter. Lower ratios, down to about three ridges  410  to each light emitter, are possible but may begin to provide incomplete blending of light emitters as viewed through face plate  160 . Second, ridges  410  that are near horizontally outer edges of face plate  160  and apertures  125  reflect a portion of light reaching them both toward, and away from, the horizontal direction in which such portion of light reaches them, such that a viewer will not see significantly brighter or less bright regions within an aperture  125 , even if light emitters  110  are concentrated near the middle of that aperture  125 . This is demonstrated more fully in  FIG. 10 . 
       FIG. 10  is an enlarged, top plan view of a portion of face plate  160 , along with a corresponding portion of reflector  150 . In order to fit within a luminaire subassembly that mates with other luminaire subassemblies to provide a four-sided pole luminaire having a sleek, tailored appearance at its corners, reflector  150  and face plate  160  are typically very thin at their edges so that the subassembly can form an angle of 45 degrees or less (for example, see  FIGS. 5A and 6B  showing sides  212  at such angles). It is extremely difficult to provide this and simultaneously provide light engines that can illuminate an aperture  125  that is “fully flashed,” that is, exhibits bright light at all viewing angles that lie within significant extents of an associated photometric distribution, across the entire aperture  125 . Referring momentarily to  FIG. 11 , this means that bright light will be seen across the ±50 degree, horizontal photometric distribution shown.  FIG. 10  shows an arrangement of face plate  160  and reflector  150  that meet the geometric constraint at the same time as it provides light across, or nearly across, the full aperture. Consider a point B that is near the edge of the corresponding aperture. Two viewers at different viewing locations will see point B along lines  430 - 1  and  430 - 2  respectively (lines  420  and  430  are drawn as “backward ray traces” in  FIG. 10 ; that is, the arrows provided are opposite to the direction of light propagation that would occur from the corresponding luminaire subassembly). Without vertical ridges  410 , the viewer along line  430 - 2  might see light from light emitters, because line  430 - 2  lies along a direction from the light emitters to the viewer (see line  420 - 2 ), but the viewer along line  430 - 1  might not see light, as the direction from point B to the viewer is opposite to the direction from the light emitters to the viewer (see line  420 - 1 ). Ridges  410  provide not only significant modulation in a horizontal direction. (side-to side, in the view of  FIG. 10 ) to blend light from light emitters that are distributed in horizontal rows, but also provide relatively planar surface portions that are close to a surface normal of the face plate (that is, having an azimuthal component that is within about 15 degrees of direction N, in  FIG. 10 ). Point A shown in  FIG. 10  is such a planar surface portion. Light that originates from a light emitter along line  420 - 1  reaches point A and totally internally reflects from an internal surface of one ridge  410 , emerging from face plate  160  at point B along line  430 - 1 . A different portion of light from a light emitter, traveling along line  420 - 2  will be refracted by another ridge  410 , will also reach point B, but will then emerge along line  430 - 2 . Thus, vertical ridges that provide planar surface portions that are nearly normal, can not only blend light from multiple light emitters, but can also reverse horizontal direction of enough of the light, that the aperture appears “fully flashed” across a wide range of viewing angles. 
       FIG. 11  shows a polar plot  500  of photometric distributions for a three-aperture luminaire subassembly for a pole luminaire as described herein. A horizontal distribution  530  is shown as a solid line, and a vertical distribution  540  is shown as a broken line; both reflect far field distributions of light from the luminaire subassembly being at the origin of the plot (an intersection of vertical axis  510  and horizontal axis  520 ). Horizontal distribution  530  illustrates the horizontal spread of light that exits the luminaire subassembly at a vertical angle at which peak light intensity is emitted by the luminaire subassembly (approximately 28 degrees downward from horizontal), thus horizontal distribution  530  is confined to areas below horizontal axis  520 ; that is, no light from the luminaire subassembly is directed behind the subassembly. Similarly, vertical distribution  540  illustrates the vertical spread of light that exits the luminaire subassembly in a vertical plan that is perpendicular to the apertures, thus vertical distribution  540  is confined to areas to the left of vertical axis  510 . The photometric distributions show a substantially symmetric horizontal distribution with significant extents out to about 50 degrees on either side of vertical axis  510 . This type of horizontal distribution is suitable for uniformly illumination all the way around a four-sided pole, that is, with similar luminaire subassemblies on all four faces of the pole, the edges of the horizontal distributions on adjacent faces will overlap somewhat. The vertical distribution is narrower and concentrated in a downward direction, peaking at about 28 degrees downward. As noted above in connection with  FIG. 3 , a significant majority of the vertical distribution lies below the horizontal. The major refractive and reflective elements of light engine  100  direct light only into angles that are below the horizontal; the only light that is emitted above horizontal is due to phenomena such as internal Fresnel reflections and scattering that direct very small portions of light into upward angles. Thus, there is very little light emitted outward (which may form undesirable glare) or upward (which may form undesirable light pollution). 
     The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of the present invention. Further modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of the invention. Different arrangements of the components depicted in the drawings or described above, as well as components and steps not shown or described, are possible. Similarly, some features and subcombinations are useful and may be employed without reference to other features and subcombinations. Embodiments of the invention have been described for illustrative and not restrictive purposes, and alternative embodiments will become apparent to readers of this patent. Accordingly, the present invention is not limited to the embodiments described above or depicted in the drawings, and various embodiments and modifications can be made without departing from the scope of the claims below.